This what Daniel Waters (https://diaboliquemagazine.com/episode-13-a-conversation-with-daniel-waters/), the screenwriter for Batman Returns (http://www.warpedfactor.com/2015/07/10-things-you-may-not-know-about-batman.html) has to say about the supposed similarities:
“Jeez, I didn’t even know there was an episode like that. Didn’t even know I’m a plagiarist […] I did watch every episode of the TV show (https://www.tor.com/2016/05/06/holy-rewatch-batman-hizzoner-the-penguin-dizzoner-the-penguin/), I was a fan, but I wasn’t like oh please lord let me one day do a Batman movie.”

I always took it as a coincidence (which apparently was the correct way to take it). A mayor plot makes more sense on the '60s TV show because Penguin was in his original "gentleman criminal" form. I'm not knocking DeVito's version. Batman Returns is actually my favorite Bat-Flick and Danny DeVito's Penguin is my favorite incarnation of the character, and one of my favorite comic book superhero movie villains. Maybe my favorite.