With whom is Gatka martial art associated with?

Turbans in the picture gave it away.

This art does NOT exist exclusively among the Sikhs. They may have modified it in some way by adding their own techniques, but it's still practiced by many in Pakistani Administered Kashmir and the (West) Punjab.

Olly, plenty of Rajasthani men wear turbans

Tina M. - Are you sure you're right when you say that Hindus wear turbans? As BlueEyedAlien wrote, I only know of Sikhs wearing turbans

Ali *Regulus* Mirza, didn't see the word "exclusively" used in the explanation