Those are the odds from razed.com... just look at how Arsenal are heavily favored to win this match.
This makes sense, as Nottingham Forest recently fired their manager due to a conflict with the club's owner and that gives Arsenal an advantage due to Nottingham Forest's still unstable situation.
This time, Arsenal will also be playing at the Emirates Stadium with their best starting lineup, which should give them a higher chance of winning.
If they still can't win this game with that much of an advantage, I don't know what else to say.