It will help keep the tube inside the tire but the patch isn't remotely strong enough to keep the tire from distorting at the cut. A tire casing boot is what you want. Park makes one. I make them from real dacron saicloth from a scrap a sailmaker gave me years ago. Quality duct tape would give you a better temporary repair than a tire patch. (Use a big piece and stretch the tape so it is closing the cut. Two later would be better.)

I use tire patches for small holes where all I am asking it to do is keep the tube where it belongs. Nail punctures and the like.