Ryu Kaze at Wikipedia. He speaks japanese and is a big FF fan. He translated SE's Ultimania guide interviews where the link is discussed.
EDIT: And apparently our EoFF Ryushikaze does tooWell done Ryu #2 !!!
Here's the "evidence":
- On VII we have "Mako" and "Materia" which energize machines, just like Pyreflies and spheres (of pyreflies) do in X.
- On X2 Shinra tells YRP about using the Farplane energy to power a city. If you get Rin as the culprit on the Mi'hen Road mystery he also talks about it: He is funding Shinra's research on harnessing the energy of Pyreflies. Shinra has a piece of Vegnagun (which apparently used Spira's energy as "fuel")
- On X2's Ultimania guide there is an interview with Nojima (not translated by Ryu, translated 2-3 years ago by some other guy) where he says X and X2 are "ancestors" of VII. But Spira is not VII's planet, somehow Spirans left to colonize other planets and found Gaia, where VII takes place
- On VII's (or X, can't remember) Ultimania guide there is another interview, translated recently by Ryu Kaze where yet another SE bigwig mentions the connection.
And finallly, there's this article in EoFF Wiki, which goes into detail on the similarity between ALL the FF games, in reference to pyreflies and memories
http://www.eyesonff.com/members/wiki...OfFinalFantasy