looks good - those curtains look a little flat though. and why do they go behind the screen at the top and bottom?

also - the walls look a little empty - might be nice to get some art deco looking lamps on them and maybe add some other details as well.

you should also stagger the heights of the seats - you don't really get seats all on the same level in a cinema.

as for populating the theater you could maybe use instances? or just put a really crappy film on the screen - so that it doesn't matter that it looks so deserted.

last, let's get some trash in there - lots of it - i've never gone to a cinema that didn't have a shed load of trash on the floor!