Yeah, suggesting the content of an episode dictated that episode's ratings (e.g., how many people tuned in) is like suggesting the quality of a movie dictates it's opening weekend numbers - it can't, because people haven't seen it yet. The following weeks determine how well-received a movie was by its audience, as that's when word-of-mouth takes over. If the quality of an episode efffects any ratings at all, it would be the FOLLOWING week's ratings, as the episode either made you want to tune in to see what happens next, or it didn't.
The only thing about an episode's content that CAN effect that very episode's ratings is, like with movies, it's marketing. Really good promo can boost ratings for an ep, but not the quality of the ep itself, since no one's seen it til they've already tuned in.