That’s up to you. Most tutoring takes place on an evening or weekend unless you are working with home-schooled children or within a school environment. You will also need to dedicate some time to organising the resources for the lessons.
But from what I have experienced the number of hours you work is at your discretion. There is enough work out there for a good tutor to have more work than they can cope with or you can just decide to limit yourself to a couple of hours a week.
Decide what suits your lifestyle and work with that.