Yes. You can freeze these patties both before or after baking, keeping in mind that tinned tuna is fully cooked before being canned. Form unbaked cakes/patties and freeze them in a single layer before transferring to an air-tight container so they keep their shape. That step isn't necessary if freezing cooked patties. For either method, placing a sheet of parchment or wax paper between layers will prevent them from sticking.