I was the only employee fired for theft when there were many of us, can I sue my employer?

Not legal advice but Unclean Hands Doctrine applies to most employment matters. If an employee has done something unlawful, for example taking property / money which does not belong to them, misrepresented material facts on an employment application (i.e. including relevant training, education or experience which the employee knows to be false but represents as true), or committing some other relevant and material act which calls into question whether the employee is trustworthy with essential job duties which include collecting money it's often a problem. There are exceptions, such as being paid below minimum wage, but those are very limited and require a careful analysis of the specific facts of each situation. In your case, you admit that you were not entitled to the money and no other allegations point to wrongdoing or unlawful pay practices by that employer. New York has many unique to New York Labor Laws. The food industry includes many practices which may rise to being unlawful. Reaching out to a labor and employment lawyer might be a good idea. They will need to collect more information about the details of how you were paid, your pay history, the agreement you and your employer made, and the actual hours you regularly worked. If other pay laws were not followed by the employer a demand letter might be an option but your "stealing" admission will not disappear. If everyone on the interstate was driving 90 mph but you were the only one pulled over by the state police would your carelessness be excused? Probably not right?