We do know how disney calculated it, because it is dictated by building codes. Occupancy is related to one thing and one thing only... getting people OUT of the building safely and quickly in case of a fire. Occupancy is allocated not just to spaces where people tend to congregate, but also to storage and bathrooms and ancillary spaces and lobbies etc. Architects pretty much will design something to reasonably fit the number of people who are going to be using it... and for a restaurant that is not just diners but also waiters, managers, food delivery people, people waiting in the lobby, people coming in to use the bathroom and not stay for a meal, people coming in to look at the menu. Even if every seat is filled (which is never the case, at least some number of tables are always in some state of being turned over since Disney staggers seatings and doesn't just suddenly seat an entire restaurant full of people at one time) you are not going to be in danger of going over occupancy. It's just not how things are designed. Not only would a restaurant lose money designing their restaurant for some number short of 100% capacity, a building inspector would never allow a business to out of its own moral sense purposely keep their capacity low to meet occupancy. It makes no sense and enforcement would be a nightmare. The time this is really hard to enforce is in bars and nightclubs where there is a set square footage per person that is accounted for to calculate occupancy but you can actually cram a lot more people in as everyone is standing. At that point yes, for safety reasons they do have someone keeping an accurate head count at all times (which is why you have lines outside of these places). There is also a reason that fires at nightclubs are so devastating - because if they go over occupancy and there is a fire you just cannot move that volume of people out of the building in a reasonable amount of time. But we're not talking about that. We're talking about a restaurant that was designed and built from scratch by disney for the purpose of being a restaurant.