Is there a certain required height a sink drain pipe must be above a floor drain (this is in a restaurant) or can the drain pipe go directly into the floor drain?

You are referring to a " indirect waste". This is when the drain pipe terminates above the floor drain. There is no direct connection. Chapter 11,section 1104.1 of mt code book states: The gap between the indirect waste and the building drainage shall be at least twice the diameter of the drain served. Good luck, Tom

Our code says it must have a minimum of one inch gap.