They could be all dead. In fact, that's probably confirmed since the title said there was only one survivor of Return to Roanoke.
But more realistically, there are at least four cameras in every room, so they are not going to be watching every single feed. The usual way to do this is to review the footage later and edit it after the fact. At the point Evan is killed, there was huge drama happening that they were probably focusing on.

We have to assume everything Sidney says is a lie. He knows he's always on camera.

On the preview clip for nest week's episode they briefly showed Sidney reacting to some event (or footagehe was in front of a bunch of screens I think) saying people will be hooked after seeing whatever he just sawI'm guessing some exciting or drama filled moment with the people in the house.

I'm assuming the crew members watching from the trailers are all dead and will be found in a later episode. As for whether it's streaming to a studio somewhere? No idea. I'm sure we'll get some sort of explanation, even if it's a forced one.

The ghosts probably somehow cut off the video feed. Ghosts are awfully tricky like that.