As far as I know, Tidus wasn't dead, as technically he wasn't alive to begin with, he was only a dream of the Fayth. For this reason he was able to go into the Farplane without any worries of disappearing, and for the same reason Yuna had no control over Tidus' departure.
You mean, wasn't alive during the game's events? Because I thought he WAS alive 1,000 years ago...and that the dreams were based off of the actual population of Zanarkand.

That's probably what you meant but I just wanted some confirmation that Tidus did indeed exist in the original Zanarkand, right?