No, slot machines do not pay more often with higher bets. The outcome of each spin on a slot machine is determined by a random number generator, so the amount of the bet does not affect the likelihood of winning. However, higher bets can result in larger potential payouts if a winning combination is hit.

There is no evidence to suggest that the odds of winning at slots are affected by how crowded a casino is. Slot machines operate on random number generators and are regulated to ensure fairness, so the number of people in the casino should not impact your chances of winning.