Ticket Sales: Fans come, when you win. If you lose, they stay at home - that's basically it.
Merchandise: A PR-manager will increase your merchandise, but i don't believe he will get back what you pay him.
I tried it for a couple of weeks. Had a level-3 PR. He wasn't worth it. Have a level-1 since then and my merchandise (and ticket sales) increase, since i start winning - despite of level-1 PR manager.