probably 5 players max; maybe it could be one player is the night guard and the other 4 are the robots (unless a 6th player would want to be the phone guy who only is there to say a few lines)
It would be better to take the idea and theme it instead. This would be reasonable to event to be single-player, but attempting multiplayer for this sort of thing (where players are the animatronics) would not be balanced because your average player will not build tension. They will rush the door and stay there.
If you want to make this work in its own way, I would recommend re-imagining the game in its own way. Have there be one "camera" guard, and a few other guards as well. Make bots that walk from room to room, and if they enter a "move" sequence while a guard is in the room, they attack them. If you want a PvP aspect, have one player sit in another "camera" room, and control the animatronics through their own door. This player can teleport to various rooms and disable the cameras in rooms, forcing the guards to go out and fix the cameras.
This turns gameplay from "snorror" into a bit of a "command your troops horror". You tell them what rooms are safe, and lead them to fix things, but you have to keep an eye on yourself too else you'll get killed, and someone will need to take your place. The person playing the "baddie" may be able to knock out guards, and leave them for dead if the animatronics find their way in.
Bottom line is you're attempting to make what I did back in 2011 with Slender, and to be honest, the outcome will be much better if you use your source material as inspiration but not for recreation.
