Here is the full list of all 13 Mafia Gambling achievements.
Achieve victory at the Dreadful Refuge underground club
Achieve victory at the Blood Hound bar
Achieve victory at the Heavenly Spire casino
Achieve victory at the MAJOR casino
Purchase all accessoires
Win 7 times in a row
Lose all your chips
Accumulate 10000 Chips
Get 21 points on your first two cards
Split cards 50 times
Get two aces as your first two cards
Get 21 points with three sevens
Reach Level 50