I have HPR's, and have
NEVER had to use aversion therapy to stop a dog jumping a gate. They jump fences all the time.
EXCEPT the ones round my garden. Which are only 3' tall. Viszlas are a bit..., how shall I say this without getting shot

.... highly strung in comparison to some. I would start teaching him TO jump. On command. That way you would be able to stop him jumping the gate by teaching him that he was only allowed to jump it when you tell him to ;)