Depending on your set-up, 2-4 people.
On one site, I'd say 6 is the max (2 in the car, 4 in a tent) ... I've never camped with just one site though, so that might be on the high side.
I say 4 comfortably. Take your tent down each morning for more space during the day.
12/26 Mystic Braves - Soho SB
12/30 together Pangea - Echo
1/4 Whirr - Echo
2/28 Caribou - Fonda Theatre
5/31 Neutral Milk Hotel - Ventura Theater