I rushed on Wednesday (July 4), which only had a matinee. I was there at 8:30 and was the ninth person in line. I'm not sure how many tickets they were selling, but by the time the box office opened, there were probably around 30 people in line. My ticket was last row of the center mezzanine on the aisle.
I rushed Tuesday for evening show and there were around 7 people in front of me when I got there at 8:30am. Note that this was a weekday and with it closing soon, you might want to get there earlier esp on the weekend. All the rush tix are the least row of the mezz but the theatre is so small that we saw everything just fine.