Me and a couple of other guys on here done one in Milton Keynes not to long ago, it wasnt my job so i dont know how much was charged but between 3 or 4 of us we were getting through a i think about 3 screens a day and each screen had a good couple hundred seats.
So on your own i reckon you could tackle a screen a day no problems, but you really need a helper with you, with a helper you can do 2-3 screens a day.
As there was a few of us on site we tried various chems and methods including ms and mini-tex, but in the end found the best thing we had between us was "Alltecs fabric pre wash" i wouldnt mess about with pre-spraying that many chairs just mix it up in a bucket and slosh it on and aggitate with a hand mit. Its really fast acting so needs hardly any dwell time.
The best way to do it is one pre treating and aggitating and one following up with hwe, you will prob get away with just pre treating the actual seats and arms and just mist and extract the backs.
If its a cinema theres probly gonna be loads of gum, and as its gona be a enclosed area with lots that will need doing the smell from most chewing gum removers will knock you out
so i would suggest you use the solutions one as its odourless just spray it on and use there metal brush it does take a while but its the best way of doing it
And dont forget to set your machine up (i take it you will have to use portable) in the centre of the middle isle else you will be forever moving it about to get to different sections