Pretty sure SE confirmed that Ivalice in both worlds is the same, but so many centuries apart that they might as well be different worlds.
You know what? I don't want a connection between XI and XIV, even more than what they already have with all the same races and such. XIV: ARR has enough potential on its own that they don't need to reference XI to have enough content to play with. XI at this point is so bursting with content that they're restricted by the initial programming more than they are imagination. XIV, if it is built and programmed properly, won't have as many restrictions.