Yes, it's the same mount. The only difference with the T4i in terms of lenses is the STM (STep Motor) technology. If you're buying a camera that has STM, then you should get at least one STM lens. The EF-S 18-135 STM lens is a great, all around lens.
I don't know if the T3i is compatible with EF-S lenses or just EF, but note that the T4i is compatible with both whereas most Canon EOS cameras are not compatible with EF-S. The difference is that the EF-S mounts the lens closer to the sensor.
Also note that the T4i and the T5i are exactly the same camera. There was a defect with the grip material on the T4i which was fixed, but the damage to the model's reputation made it so that reissuing the same camera with a different model number was a wise idea.