Betta Fish: Is this tank okay for a betta

Bettas like to lay on leaves and hide. The tank itself is good and what you have already is ok to leave in, I’d probably only recommend 2 things here.
A. Remove the ornament on the right, especially if it has any sharp edges the betta could cut or rip its fins on
B. Get some anubias, they look great, provide something for the betta to hide under and rest on, just make sure you keep the rhizome out of the substrate (only bury the roots) otherwise it’s likely to rot.

Would be better with a better filter, like a large sponge filter (with the foam part AT LEAST as big as a soda can). Ignore the manufacturer’s tank size ratings.