Yeah, the Ivalice Alliance games are all connected! The "War of the Roses" version of FF Tactics even has a time displaced Balthier as a playable character! The FF12 Era titles are usually thought to have taken place in the first age, where there was still a lot of magic, technology, and other races. The FF Tactics games are thought to take place far later in time, they unearth relics of the more technologically and magically advanced ages before them. However, notably, the world of FF Tactics seems to have lost most of the other races, and their society has regressed to more properly medieval standards. The reasons for this are unclear, although many fans theorize a horrific calamity or something like that.