Titanfall will be making its way onto the Xbox One soon along with the PC. EA announced this and also said that owners of the PS4 should not expect the game to arrive on their console anytime soon.
The developer has been working with Microsoft closely and only then approaching Sony. EA have said that is about marketing and loyalty. Once dealings with Microsoft have settled down, EA will then consider taking the game to the PS4.
Respawn said that Titanfall would discard the single player feature thanks to the fact that more players want to play online. Of course Xbox Live is the perfect platform for this.
However Xbox One users have to bear in mind that the game is action oriented and as such it will not have support for Kinect, therefore players will have to make do with controllers. Kinect players could find this disturbing, but they should also take into account that PS4 owners will still be waiting to get their hands on the game.