Originally, it was 20,000 tickets in the stands and 15,000 on the field. I noticed that there are 20 sections in the old seating configeration they were using prior to the Grammy's. That means there are about 1,000 seats per section. It looks as though they have opened up potentially another 6,000 seats just in the stands. If they are willing to add the same ratio of tickets for the field, this might mean up to 5,000 more GA's on the field.
Potentially, they may be attempting to stuff another 11,000 people into the show, for a total attendance for one show of 46,000. It will definitely be easier to sell 11,000 more tickets than it would be to sell another 35,000, especially since none of the new tickets are at the $165 dollar price.