UPDATE: According to the website Dualshockers who spoke with Respawn Community Manager Abbie Heppe, Titanfall does not consume ‘up to 40GB’ on the Xbox One after all. Instead, Titanfall will be a 20GB download, and will only consume 20GB storage space in total.
Respawn initially confirmed the Xbox One download size for Titanfall will be 20GB which we assumed was the ‘installation files’ necessary to install the full game on your console. Claims of Titanfall requiring ‘up to’ 40GB of Xbox One storage surfaced during the announcement of the Xbox One Titanfall bundle.
Abbie Heppe states the discrepancy with installation sizes may be down to the fact that packaging for the Titanfall Xbox One bundle was done before the install size of the game was actually finalized.
Microsoft posted on Xbox Wire, in small text, that install for Titanfall will require 40 GB of space on your Xbox One.
“On Xbox, Titanfall requires Xbox Live Gold membership. Titanfall game download card inside marked packages; up to 40 GB required.”
That seems to line up with other Xbox One games. BF4 is around 30 GB.
SOURCE: Xbox Wire