That's hard to figure. From the description, it sounds like only parts of the MK are open for this, so that makes it more difficult to estimate as well. It probably was up to DVC how many people they wanted to pay MK for to have this event. Park capacity before the hub redesign and new fantasyland used to be around 75,000, now I think it's a bit more. I think it's reasonable to assume that DVC made the event to be up to 50,000, but that would be an upper figure, and it's probably less. We're guesstimating here, but probably somewhere between 25,000 and 50,000. I know all the WDW studios and most 1 bedrooms are sold for that first night, so when you start to do the math...