There are 6 cabin jumpseats and one in the flight deck on a 320. So that’s 7. However, if the crew complement goes above this number then cabin seats will be used (not that this happens in the day-to-day operation).
I believe the company are playing around with crewing levels this summer on high take up BOB flights to see what works. I came back from one of these destinations the other week with about 50 pax and 6 crew.