Below you can see the front-view size comparison of the Olympus E-P5 and Fujifilm GFX 50S. The Olympus E-P5 is clearly the smaller of the two cameras. Its body is 26mm narrower, 25 mm shorter and 54 mm thinner than the Fujifilm GFX 50S.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.