EDIT: Sorry my Math was wrong. At five dispatches every minute and 3 seconds reported by LCA sources, that's actually a dispatch rate of 63 seconds / 5 dispatches = 12.6 optimal dispatch time. 3600 seconds / 12.6 seconds per each dispatch = 285 dispatches per hour. 285 dispatches per hour x 4 passengers per dispatch is around 1100 passengers per hour, again based on a single anecdotal observation of dispatch testing in Japan.
They are obviously not dispatching this thing every 12.6 seconds with pinpoint accuracy, so if we assume 15 second dispatches at worse, then we get 3600 seconds / 15 seconds per dispatch = 240 dispatches per hour -> x 4 passengers per dispatch = 960 capacity.
EDIT: I guess to clear up any confusion, I had assumed they based their capacity calculations on track length, but it can (and should as
@UniversalRBLX points) be derived entirely from observed dispatch rates.