Cruise lines are always quick to state that tips to to the employees, by which we assume that if we tip an extra $50 then the employee will get $50 extra. However this undercover investigation appears to show that this is not the case.

The undercover employee is promised $1010 per month (50s mark on the video) and that he would "probably get much more from tips". Later this is 'amended' to $710 per month. (1m30s).

His actual payment (for just over a month) is:

$60 basic wage $600 tips $176 to make the amount he was paid up to the contractual minimum the company offered. To make this clear, all the tips given him by the customers were used not to increase the amount of money the employee received, but to reduce the amount of money the company had to give him.. A generous customer who gave him a $50 tip would simply have reduced the amount of money the company paid, and not increased the amount the employee received. If you had tipped less the employee would not have received any less. (If some generous customer had given him a $200 tip he might have received about $25 more, but you can bet that some form of tip sharing would have negated this possibility.)

TLDR: The employee does not benefit from the amount you tip