It will all depend on when/if they close the gates and deem that the ground is 'full'. I don't know if it's the club, the police or a Council officer who decides this. I think I'm right in saying that the club has a crowd cut-off figure of around 20,000, showing that it has 'shrunk' in capacity from the 1980s halcyon crowds.
I do know that the club will need to have more efficient people on the gate as I'm told by some walk-up friends to the Cronulla match that they were in a queue for one hour trying to get in.