Interesting one since it is Spotify that is trying to close the currently open podcasting universe.
Let's not pretend that Spotify is either the white knight or the underdog here. This is two big companies negotiating over pricing.
How much, I have no clue - but if they can't even have a "get premium now" button in the app then that's insane to me. The 30% fee Apple would take isn't a real alternative either, it's still not profitable.