Ubisoft has confirmed that the For Honor Closed Beta will be taking place from January 26th to January 29th on PS4, Xbox One, and PC. Along with the closed beta there will be an event called War of the Factions which will track all of the multiplayer activities across the three platforms to determine whether the Vikings, Samurai, or Knights are the best faction. There will be rewards which will be exclusive to closed beta players.
If you want a chance to take part in the beta then you need to sign up through this link. For Honor will be released on February 14th.
Source: Press Release