If the game is being carried on ESPN (most ships have both ESPN1 & 2) then it will be shown.
FWIW: yes, most important games do get shown on ships, but there is no guarantee. It won't hurt to inquire as soon as you get on board so the right people get the message that this is an important game to Americans. Sometimes the Crew doesn't always know what games we want to see - but they wouldn't miss a soccer playoff for anything.
If it is on a channel they can access they will do it.