Not all of the time, but some of the time you can decide what Noel says. Final Fantasy XIII has dialogue trees and unlike Sakura Wars the game waits for a player to select an option.
Deep into the demo, the duo discover an artifact. Part of rebuilding Coccoon, it seems, is tracking down relics. When Noel discovers what he was searching for text choices popped up. Each one was linked to a different button similar to Mass Effect. What does Mog think? What does Alyssa think? and I live in the moment were three of them.
It isn’t clear how these effect the game from a demo alone, but it appears players will be able to impact the game’s story to some degree.