No sorry it won't. This adapter is to use Canon EF and EF-S lenses on a Micro 4/3 camera body. 

If the gh4 is a micro 4/3rds system then it will work. I have quite a few Nikon and Sigma lenses including the 50mm afs and they all fit and work perfectly. You will have to set your aperture and focus manually but the camera will make all the necessary exposure adjustments itself. Don't forget on a 4/3rds system your 50mm will be 100mm based on a full frame. Make sure your camera is a micro 4/3rds and not a 4/3rds, I have both. 

Don’t forget that it’s a manual lens adapter. Works with full manual lenses. If your lens has no physical aperture ring, you cannot control it from your camera 

No Allen wrench comes with the unit and I did not need one. Mine did not require any adjustments and fit like a glove. 

Hi, this adapter is for Canon EOS mount lens to Sony E NEX mount camera, we checked the sony a 7iii camera mount is E mount , this adapter can fit it , but you can reconfirme it , thanks. 

Yes, it is indeed Nikon f mount. 

Hi, this adapter is for Canon EOS mount lens to Sony E NEX mount camera, we checked the sony a 7iii camera mount is E mount , this adapter can fit it , but you can reconfirme it , thanks.