I was flipping through some wikis and saw that the Final Fantasy VII characters have birthdays with their year stated. After browsing around for a little bit, I couldn't figure out where they got the year date from. I was hoping anyone here can point me in the right direction?
I.E.
Yuffie Kisaragi's birth date is November 20, 1991.
Barret Wallace's birth date is December 15, 1972
I'd generally be inclined to say it's a meaningless question, there being no system of dates established in the game (to my recollection). Pretty much everything in terms of years are just spoken about in reference to the present (e.g. 5 years ago, 7 years ago, etc.), so you might as well regard FF7 as taking place in Year 1, Cloud leaves Nibelheim in Year -7 and so on. I'm also inclined to believe those birth dates you mentioned were completely made up by someone.
However, if those dates have any legitimacy to them, it should be pretty easy to establish the year of FF7 to at least within 1 year using the ages of the characters. For example, if my memory is accurate, then Yuffie is 16. I think Barret is in his 30's (though I don't remember the exact age) so those dates for Yuffie and Barret could at least be consistent with their ages. Anyway, Yuffie's age together with that birth date would place FF7 in 2007 or 2008 of its world (2008 being more likely given how late in the year she was born, but either is possible). You could constrain it more using all the characters' birth dates, but then it's also possible you'll run into contradictions.
It takes place in 0007 of the fictional εγλ calendar. The timeline begins over two-thousand years before the calendar system is introduced in Gaia and then goes from 1877 (Bugenhagen's birth) to 0507 when the epilogue of VII shows with Red XIII and his kids. For stylistic reasons, instead of jumping to 2000, the calendar switches to 0000 so we could have that perfect 0007 number be the year FFVII actually takes place.
The info comes from the 10th Anniversary Ultimania for FFVII. It should be noted that the timeline was written during the Compilation of FFVII period, so the timeline is a post-VII creation.
Final Fantasy VII takes place in late 0007, early 0008, about ten years after the date of its real-world release.
Source: finalfantasy(dot)fandom(dot)com