Anyway, to the OP, the big question you may need to face is how to define the "look" of the GIF animation...I don't think you can show motion like you could in a video, so decide you have to what your individual frames will consist of to give the approximate/relative look.
One idea would be to take a series of shots with a "medium-slow" shutter speed -- it would depend on how fast the fan is spinning, you'd have to experiment, the idea being that each shot would capture a bit of the fan "in motion", showing "motion blur". Or, a series of fast shutter speed shots, each that would "freeze" the motion of the fan, and combine them together the animation could cycle through a complete rotation...
As to a person standing in front of/below the fan, you may be best to get one shot of the person, then multiple shots of the fan (no person) then clone the static person into each "fan shot"...