As far as I know there are no parking deals in place. A lot of people stay at a hotel the night before the cruise, the hotel has been known to allow guests to park long term for a decent fee. Keep in mind that parking in NYC is very pricey. You should find out which hotels work with the cruise line of your choice.
Between $30 to $40 a day https://www.nycruise.com/manhattan-terminal/parking/
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