Need to add fans to my case to improve cooling and unsure what would be the best placement of fans

I have define R5 case, 4690k and gigabyte gtx 970 g1. My cpu is watercooled and the rad is 240. Currently i have 1 intake on front(140mm), 1 exhaust on the rear(140mm) and 2 exhausts on top on the radiator(2x120mm). I was thinking of adding anothing 140mm intake on the front, and 140mm intake on the bottom for the gpu, and 140mm exhaust on the side for the gpu, would this be a good setup?

would it not help exhaust the hot air coming out of gpu?

What Kewldude said. Always aim for positive pressure.

I'm not sure how much improvement you're hoping to get, but for that setup you already have more than adequate cooling. You just need to work on it a little.
Get rid of that rear exhaust and turn it into a front intake. If you really insist on more fans, keep the rear fan where it is and get a second front intake and another fan at the bottom.

My advise: get 2x140, mount one on the front, mount the other on the floor to blow directly upwards towards the GPU. At the end of the day you will have 3x140 intake, 1x140 + 2x120 exhaust. Set your 140 exhaust on 5V so it will be fairly quiet, set your intakes on 7V and you are golden. I have 5x140 set to 7 volts in non silent case and it is all so quiet...