Kitase, lead developer of the FF series (FFX was especially his baby) and Nojima, "scenario writer" for FFVII/FFVIII/FFX/X-2, both hinted at connections between FFVII and FFX in the FFX Ultimania guide. FFX-2 made that connection explicit, although the in-game dialog is fairly hard to get, since it only appears if Rin turns out to be the culprit in the Mi'ihen Highroad Mystery.
When confronted by the Gullwings, Rin admits that he concealed the dangerous machina accidents because he and Shinra have a plan that's too important to let people be scared away from machines again.
Rin "We are researching ways to extract the vast energy that sleeps in Spira, and use it to power machina."
Afterwards, if you talk to Shinra on the airship:
Shinra "Aha..." Yuna "What are you looking at?" Shinra "Farplane data." Shinra "The more I study it, the more fascinating it gets. There's limitless energy swirling around in there." Yuna "Limitless energy?" Shinra "The life force that flows through our planet...I think." Shinra "With a little work, we could probably extract the energy in a useable form." Brother "Sweet!" Shinra "Of course, that'd take generations." Brother "That's no fun!" Buddy "Well, still, it is something worth shooting for." Yuna "Think how much Spira would change if we ever got it to work!" Yuna "Maybe one day we could build a city full of light, one that never sleeps!" Shinra "No doubt about it."
=====
But Spira is not the same planet as FFVII's Gaia, as we learn from the X-2 Ultimania....
***Interview with FFX-2 creators from the Final Fantasy X-2 Ultimania*** (Page 723)
Nojima "...After quitting the Gullwings, Shinra received enormous financial support from Rin, and began trying to use Vegnagun to siphon Mako Energy from the Farplane. But, he is unable to complete the system for utilizing this energy in his generation, and in the future, when traveling to distant planets becomes possible, the Shin-Ra Company is founded on another world, or something like that....... That would happen about 1000 years after this story, I think."
--"So VII's story is after that?"
Nojima "Well, you could say the feelings I have are like that. When I think about the characters, those are the kinds of feelings I already have. Shinra is a good child, but his descendants are going to end up becoming like the president [of Shin-Ra] (laughs)."
Watanabe "With you said about VII, after seeing your episodes with Shinra, one of the people on the [development] staff said that the first shot of the Bevelle Underground 'gives the impression of somewhere else.'"
[Motomu] Toriyama "Certainly; it looks like the opening shot of Midgar in VII."
So the connection between the two games wasn't entirely hashed out. My impression is that towards the end of working on FFX, Nojima thought, "hey, this whole farplane/pyrefly idea mirrors the lifestream idea we had in FFVII...maybe there's a connection." And then, when working on X-2, he (?) created the character of Shinra, boy genius, as a tie-in, and threw in that hidden cutscene implying that his descendants founded the Shinra power company.
Which also implies that the Cetra of FFVII are actually from Spira. And Rufus Shinra's family may be Al Bhed.
But I don't think they really ironed out how to make the two games consistent; it sounds like a crazy notion that Nojima was dinking around with, and the others let him play.
====
One more note: While various official Square websites and some promotional materials for the Advent Children movie refer to "the Planet" as "Gaia," the word only ever appears in-game for a particular location (Gaia's Cliffs). I think Gaia is spelled out as the name of the FFIX planet? I can't remember.
Despite some ill-considered hints in original FFVII, I don't think its planet is really meant to be our Earth. The continents are a completely different shape. It reminds me of a lot of fantasy worlds that are based superficially on the real world, but are not intended to be our world in an alternate history, future or past.
There's two in-game things that muddle the issue.
1) Sephiroth's ridiculous Supernova overdrive shows some kind of mega flare blowing apart each of the planets of our real-world solar system -- labeled "Jupiter" and "Mercury" and so on. It's a ridiculous bit of battle/story segregation that I doubt was carefully considered. (Then again, by the end of the overdrive, most of the solar system is destroyed. So maybe that overdrive blasts our solar system but leaves the FF7 solar system untouched!)
2) More puzzling is the animation that accompanies Bugenhagen's lesson on the Lifestream. His orrery shows a solar system that matches ours, although the planets aren't labeled this time. There's a ringed planet, a red planet where Mars should be, and the planet he's using to demonstrate the Lifestream is a blue, green and white world with one moon. But Buggy doesn't come out and say, "This is Earth" (or "Gaia"). He just calls it "the Planet."
My hunch is that both the Sephiroth-overdrive and Bugenheim's planetarium demo were not carefully considered. There are some bits of original FFVII that don't entirely hold up later, although it's pretty robust for such a complex and detailed game. (I still want to know what happened to the Gi tribe; as far as I know, they're never mentioned again.)
Re: The FFX - FFVII connection
When confronted by the Gullwings, Rin admits that he concealed the dangerous machina accidents because he and Shinra have a plan that's too important to let people be scared away from machines again.
Rin "We are researching ways to extract the vast energy that sleeps in Spira, and
use it to power machina."
Afterwards, if you talk to Shinra on the airship:
Shinra "Aha..."
Yuna "What are you looking at?"
Shinra "Farplane data."
Shinra "The more I study it, the more fascinating it gets. There's limitless energy swirling around in there."
Yuna "Limitless energy?"
Shinra "The life force that flows through our planet...I think."
Shinra "With a little work, we could probably extract the energy in a useable form."
Brother "Sweet!"
Shinra "Of course, that'd take generations."
Brother "That's no fun!"
Buddy "Well, still, it is something worth shooting for."
Yuna "Think how much Spira would change if we ever got it to work!"
Yuna "Maybe one day we could build a city full of light, one that never sleeps!"
Shinra "No doubt about it."
=====
But Spira is not the same planet as FFVII's Gaia, as we learn from the X-2 Ultimania....
***Interview with FFX-2 creators from the Final Fantasy X-2 Ultimania***
(Page 723)
Nojima
"...After quitting the Gullwings, Shinra received enormous
financial support from Rin, and began trying to use Vegnagun to siphon Mako
Energy from the Farplane. But, he is unable to complete the system for
utilizing this energy in his generation, and in the future, when traveling to
distant planets becomes possible, the Shin-Ra Company is founded on another
world, or something like that....... That would happen about 1000 years after
this story, I think."
--"So VII's story is after that?"
Nojima
"Well, you could say the feelings I have are like that. When I think about the
characters, those are the kinds of feelings I already have. Shinra is a good
child, but his descendants are going to end up becoming like the president [of
Shin-Ra] (laughs)."
Watanabe
"With you said about VII, after seeing your episodes with Shinra, one of the
people on the [development] staff said that the first shot of the Bevelle
Underground 'gives the impression of somewhere else.'"
[Motomu] Toriyama
"Certainly; it looks like the opening shot of Midgar in VII."
-- Source
====
So the connection between the two games wasn't entirely hashed out. My impression is that towards the end of working on FFX, Nojima thought, "hey, this whole farplane/pyrefly idea mirrors the lifestream idea we had in FFVII...maybe there's a connection." And then, when working on X-2, he (?) created the character of Shinra, boy genius, as a tie-in, and threw in that hidden cutscene implying that his descendants founded the Shinra power company.
Which also implies that the Cetra of FFVII are actually from Spira. And Rufus Shinra's family may be Al Bhed.
But I don't think they really ironed out how to make the two games consistent; it sounds like a crazy notion that Nojima was dinking around with, and the others let him play.
====
One more note: While various official Square websites and some promotional materials for the Advent Children movie refer to "the Planet" as "Gaia," the word only ever appears in-game for a particular location (Gaia's Cliffs). I think Gaia is spelled out as the name of the FFIX planet? I can't remember.
Despite some ill-considered hints in original FFVII, I don't think its planet is really meant to be our Earth. The continents are a completely different shape. It reminds me of a lot of fantasy worlds that are based superficially on the real world, but are not intended to be our world in an alternate history, future or past.
There's two in-game things that muddle the issue.
1) Sephiroth's ridiculous Supernova overdrive shows some kind of mega flare blowing apart each of the planets of our real-world solar system -- labeled "Jupiter" and "Mercury" and so on. It's a ridiculous bit of battle/story segregation that I doubt was carefully considered. (Then again, by the end of the overdrive, most of the solar system is destroyed. So maybe that overdrive blasts our solar system but leaves the FF7 solar system untouched!)
2) More puzzling is the animation that accompanies Bugenhagen's lesson on the Lifestream. His orrery shows a solar system that matches ours, although the planets aren't labeled this time. There's a ringed planet, a red planet where Mars should be, and the planet he's using to demonstrate the Lifestream is a blue, green and white world with one moon. But Buggy doesn't come out and say, "This is Earth" (or "Gaia"). He just calls it "the Planet."
My hunch is that both the Sephiroth-overdrive and Bugenheim's planetarium demo were not carefully considered. There are some bits of original FFVII that don't entirely hold up later, although it's pretty robust for such a complex and detailed game. (I still want to know what happened to the Gi tribe; as far as I know, they're never mentioned again.)