Crysis 3 will be hosting a multiplayer beta that will be availible to everyone on January 29th, including PC, Xbox 360, and PlayStation 3. The beta will be updated on Origin for PC, and availible on the markets for each console. Some may have to do a bit of searching to find it on the store.
The beta will be open January 29th and end February 12th. There will be two maps and two game modes to test out. You can read the full details on the Crysis website!