The animated people are controlled by the GSX Settings "Airport Walkers", if they are disabled, they won't show up.
And, it might take a couple of minutes before they are visible, since they are not spawned all at the same time, but one by one at random time intervals, so they won't cause a big stutter ( which would happened if we created all at the same time ), and the time interval between the creation of each one, is controlled by the GSX Passenger Density slider in the GSX Timings page so, if you want to see more people, raise the slider.