am looking after my sisters dog for 2 weeks the problem he jumps the stair gates one is a dog one ( it is on the stairs) the other one is just a normal child gate they might aswell not be there. please any advice on how to stop this would be great

I don't think you're going to be able to stop this in two weeks (unless you take DIY measures to make the gates taller)  I'd be working on making sure the dog can't reach the gates to jump them if there is nobody there to supervise and distract it.  Make sure that staying on the right side of the gate is more rewarding than jumping it..

My dane used to do this to a gate we had separating the kitchen from the front room, we solved it by taking the gate away! Was too frightened of him landing funny/getting stuck/ seriously hurting himself :)