I know it's been said numerous times before, but it deffo needs to be more than 52k. It looks absolutely stunning though
Doesn't really matter. Couple of thousand more would cost more and they don't actually produce that much money. They would be high up so wouldn't be the most expensive ones. Say, £40 a pop. So a thousand spectators would mean 40k per match and over the season less than million. So say it was 5k bigger, that would increase gates by about £4m but then you have to consider how much more the stadium would cost. As Meis said, the last seats are always the most expensive. So the returns diminishes as you make it bigger.
But that's expecting full house every match for ever. What if the weather's bad or the opponents don't make your heart race? And if you can get tickets from the gates, how many would not buy a season ticket?