Apparently not much more than other first person shooters on the console.
As indicated by the recent pack shot for the upcoming Xbox One bundle, Respawn Entertainment’s Titanfall will require up to 40 GB of free space for installation on the next gen console.
“On Xbox, Titanfall requires Xbox Live Gold membership. Titanfall game download card inside marked packages; up to 40 GB required.” It’s not that big of a divergence from typical installation sizes, even on other consoles. After all, Killzone: Shadow Fall on the PlayStation 4 required almost 40 GB of install space, which necessitated the need for the “Play as you Download” feature.
The Xbox One has a similar feature and since UK gamers picking up the console bundle will receive a download code for Titanfall, it remains to be seen if said feature will be available. The bundle will be releasing on February 28th in the UK, while the bundle along with Titanfall will be available on March 14th for £399.99. Titanfall will also be available in North America on March 11th for Xbox One and PC.