Radio City Music Hall

If that is the case how did they come up with 5,000 general admission seats available? And how did this movie get a G rating?

Yes but the Music Hall has about 6,000 seats. If 2 mezzanines are used that brings you down to more like 4,000.
When selling first mezzanine seats in advance for a holiday show for example the Music Hall would always say 5,000 general admission seats available for every performance. Here they are saying the exact same thing but reserved seats are in two mezzanines. It’s pure hype. When I worked there as a doorman they would sometimes create outside lines when the performance was far from sold out or even well attended. I think Times Square theaters did the same thing. I read Mike Todd sometimes had the sold out sign put up at the Rivoli for 80 Days even if the performance wasn’t. Now on youtube I’ve been hearing that Disney has been known to buy out performances of ‘tentpole’ movies to inflate grosses and increase demand for tickets. The old showmanship is not completely dead.

The entire first mezz was always reserved seats for every performance of its move/stage show history. To say 2500 seats reserved, which itself is an exaggeration, it would have taken the entire first and second mezz.