One of the articles I read yesterday stated that in the state of New York, this type of conviction has about a 1 in 10 chance of including a prison sentence (up to four years). The judge determines the sentence, and may also weigh in with whether a monetary sentence would be meaningful to the defendant, but also things like remorse (which Trump has shown none) and the number of convictions (which are a lot).
Even if we get lucky enough to see Trump sent to jail, he can still get out on bond while appealing the case, so it could be a year or more before Trump would ever have to spend a night behind bars.