I assume that 2500 figure is both ways. Keep in mind that that figure is provided by the TfL
PR department! A frequency of fifteen seconds is frankly optimistic in practice - remember boarding/alighting time - but lets accept those figures.
Five passengers, four times a minute for sixty minutes: 5 x 4 x 60 = 1200. Both ways, 2400.
Five to six passengers plus luggage is probably a realistic maximum capacity per gondola. Ten is a squash. An MDG system would be great if there was a steady stream of passengers over the course of the hour, but totally unsuitable if a train turns up every 15 minutes and dumps say, 100 passengers on the platform all at once.