In fact, the recognized Patron Saint of Gamblers is Saint Cayetano or Cajetan, whose Feast Day is August 7.
St. Cayetano was born to well-to-do parents in Vicenza, Italy, in 1480 and was trained for a life of piety by his mother. He studied law and worked as a diplomat for Pope Julius II, with whom he helped reconcile the Venetian Republic. He was ordained as a priest in 1516. We couldn't find much pertinent information about his life and why he was selected as the Patron Saint of Gamblers (not to mention the unemployed, job seekers, and good fortune), athough one source explained that it was because people bet him a rosary or blessed candle that he would not do some special favor for them.
In his life, St. Cayetano gave his family fortune to help those in need and he promoted the spiritual life in conjunction with care for the poor and sick. According to Wikipedia, "He died of grief in Naples" in 1547, worn out by the corruption he saw around him, paticularly within the priesthood. He was beatified in 1629 and canonized in 1671.
Another saint, San Simon, is Guatemala's own Patron Saint of Gamblers and Drunks. Part Catholic saint and part Mayan god, his worshippers apparently pray to him for fertility and prosperity and his shrine, located in the village of San Andres Itzapa, allegedly receives copious offerings of alcohol and tobacco (cash is also welcomed) from his devotees to appease him. A statue of him at the shrine is described as being covered in plastic, because people "sometimes spit alcohol and Coca-Cola on him as a way to ask for his blessings."
Lastly, Saint Bernadino of Siena is known as the Patron Saint of Gambling Addicts and Compulsive Gambling, among many other things. A charismatic orator born in Massa di Carrara, Italy, in 380, Saint Bernadine was known for his mediating abilities and skill at reconciling oppenents, and for his numerous female supporters.