Are we required to have one in a standard kitchen with a gas range in a residential home? The big question is not how many CFM or ducted or not, just whether there is a requirement in the building codes. I live in New Jersey, US.
Yes, and not only do you need a fan but it must exhaust outside and not just recirculate the air through a carbon filter. You are burning fossil fuels which produces carbon monoxide (among other things). This can kill you if not properly vented.
Rather than repeat what is already on this site, per the comments, see this answer for the exact code requirements for exhaust hoods.