Yea exactly or entice a company to advertise on the podcast if they were getting such an amount of listeners etc and then offer a code to the listeners. For example Georgie Crawford and the good glow podcast has Vichy as current sponsors so they would pay her costs for recording it and the time and then they feature on it tooI don't think they earn anything per se but if you can show a brand that your podcast has x amount of following/downloads/reach then it will probably increase what you could charge for paid posts etc.