Look’s like that 2 – 5 Players will be able to play together. Rumors says, that the mp will be like in Dark Souls 2. Other rumors say, that there will be a special monster-level, in which players play deathmatch. From Software didn’t announced details about the multiplayer-part until now.
On March 25. 2015 we will know more, because it’s the release day of Bloodborne. Comment below.