Interesting which system to prefer. Money is not a factor here. Posed portratits only. 17 vs 23mm indoor and 75 vs 56mm outdoor.
Size matters. IQ too. And external lighting with softboxes and remote control.
First, you're talking about 17/1.8 vs 23/1.4 which are both equivalent to a 35mm focal length on their respective systems. However, why compare the 75/1.8 to the 56/1.2 since were talking about 150mm vs 85mm? The Olympus 45/1.8 or better yet, the Pan/Leica Nocticron 42.5/1.2 would be a better comparison. In any case, I think the Fuji 23/1.4 is the superior lens over the Oly 17/1.8 and a tossup between the two 85mm focal length lenses but the differences between them are really splitting hairs.
As for Olympus EM1 vs Fuji XT1, I was in the same boat of making a choice between the two bodies and systems. I would have gone the Fuji route, but the deal breaker for me was the D-pad on the XT1 being pretty useless in terms of it being nearly flush with the body and mushy feel. I do like the old style manual controls along with selecting aperture with a ring on the lenses. However, the EM1's ergonomics and overall feel is a thing of beauty as is the faster auto focus.
Both systems are capable of high quality images and although the lens lineup of m43 is more mature, the Fuji lens lineup is nothing to sneeze at. It really boils down to which system body feels more comfortable to use and which one is more ergonomic for you. In my case, the EM1 won out in that regard and was the one that I purchased. I will however, revisit Fuji once their new bodies are announced and released after Photokina.