The HITMAN Beta for PC is out on Friday the 19th February, a week after the PS4 beta starts.
The latest trailer gives you a glimpse of what the beta includes:
https://www.youtube.com/watch?v=3O1DnIyhA3I
We've also refreshed the information in the "HITMAN Beta - All Details So Far" thread with an extensive FAQ on what to expect. Stay tuned for more details as we get a lot closer to the Beta start date. Take a look: http://steamcommunity.com/app/236870/discussions/0/487870763317597470/