It’s possible like in the real world that he didn’t know who they were even in adventure city they were semi popular because Liberty knew who they were

It's a joke poking fun at how PAW Patrol merch sells incredibly well in the real world due to its popularity.

Gus didn't know who the PAW Patrol were because he's not from Adventure Bay or Adventure City. It's never stated where he's from, but considering he was hauling maple syrup in his truck, he may be from a "fictional" Canada in the PAW Patrol universe.