How many in a 8 x 16ft room

Are you going to leave any room for walkways to access the plants?

I don't know if I would do a room that big of autos. Photoperiods yes, way better results. but given one auto could take up a 2'x2' square or 4feet squared, There is 128 square feet in your room approx 32 plants MAX. in a 2x2 foot print per plant. That's a bit tight though. Give yourself a bit of wiggle room between them for better air flow, in that case 2.5ftx2.5ft = 6.25fs squared or even 3'x3' = 9'fs 128ft squared at 6.25' a plant is 20 plants. 128ft squared at 9' a plant is 14 plants. also have to factor in any tools and objects like water bucket or tables. Best Of Luck!