Thanks to Magus22 for finding this. The Chrono Trigger information's on the third page, though it's more about how Kitase used the time travel system as a premise to build on. Original source is here.
A lot of people have compared Final Fantasy XIII-2's time travel premise to Chrono Trigger. How far should the comparisons go?
Obviously Final Fantasy XIII and Chrono Trigger share the same theme of time travel, and obviously people talk a lot about Chrono Trigger in the context of XIII-2 and I can understand that. It's true that we racked our brains to work out how best to take that element of time travel from Chrono Trigger and express it for current gen consoles - which kinds of game mechanics would be appropriate and so on, we did think of that.
The main difference between the two titles is that in Chrono Trigger, you go back to one point in the past and you do this and that, and those changes could impact on the future. You can't really interact with what happens in the future.
But in XIII-2 because of this new feature called Historia Crux, the player can choose a location and time that they want to play by themselves. They get to make the choice about which area or era they want to explore. OK, you've played this world and that world, your characters are now a lot stronger, more powerful and all the rest of it, and then you can revisit some of the times and locations you completed before, except now as a more progressed character - which can sometimes help you find different time-gates, so that you can actually go back and go through and take a different route to another different time and location. So it opens the door to lots of different things you can explore. That's how we have advanced from Chrono Trigger, if you like.