A source tells Xboxygen that the Titanfall beta will be going live between February 14 and February 19. In the US, the beta will be available through GameStop. This is according to promotional material that Xboxygen got their hands on, posted below.
However at this time, EA has not made any official announcements.
Here is the promotional material:
Titanfall is scheduled to launch March 11, 2014 for Xbox 360, Xbox One and PC.
Edit: It has been confirmed that the Titanfall beta is on the way. Here is the latest tweet from Vince Zampella:
#supersecret announcement time. I'm sure no one has been able to guess from the leaks. PC and XboxOne Beta! Details in the coming days
— Vince Zampella (@VinceZampella) January 28, 2014