First time going to a Nets game

Hi guys, finally I managed to go to the US for the first time in my life and it has been a dream of mine to go to an NBA game, but I need your help.

I want to go to the Nets game against Kings in early April. The thing is the game starts at 19:30, but I can only arrive at Barclays Centre at 19:30 or a bit later. Will they still let me in or do they close the doors as soon as the game starts?

Thank you for your help in advance!