The question is, why do you wish to connect a brushless motor gimbal to the flight controller?
It is usual (and this is how I did my gimbal on my DJI NAZA, see https://www.youtube.com/watch?v=sYGtNW8Insk&t=534s skip to 24:00 to avoid me rabbiting on about other things) to let the gyro and control unit look after themselves as the quad moves and twists in the air and connect a spare RC channel to the Pitch control of the gimbal so that you can aim the camera up or down as you wish to get your shot. If you have another spare RC channel you could connect that to the YAW to enable you to pan the camera around. There is little point in controlling the ROLL of the camera you will need that to stay level and the gimbal control will cover that.
If this is a good answer for you let me know and I’ll try to give you an exact wiring layout
If I’ve misunderstood entirely then sorry for making you read this