I have a video and a person walks in front of where I want to put the tracked model and I didn't know if you could cut him out so the model will go behind him like in AE or if that wasn't possible in blender.
It is possible, since blender has fully featured masking capabilities. Here is a simple setup to show you how it works:
If you were able to shoot against a green screen, use this setup instead:
Note: If you need to feather a certain point on you mask, you can hit Alt-S. If you need to feather the whole mask, add a color ramp node after the mask node, you can then tweak the feathering.