That's top capacity, which probably is only at rush hour.

Most of the city's subway cars seat between 40 and 60, but there can be another 100 to 200 people standing in them.

This page has links to all the different pages of the NYC rolling stock (from wikipedia)

http://en.wikipedia.org/wiki/New_Yor..._rolling_stock

Those detail pages will show the capacity of each of the cars. Most are only showing seated, some list standing and seated.