Well, it's hard to say. That would take a lot of guts - with four of them, you'd be stressed out and nervous. It would be hard to pull it off.
Don't take any of the following as gospel; it's just my thinking, and what I've observed, generally speaking. The thing about large numbers (more than one or two) is that they tend to react more slowly - in a four-person gang, a single gunman will take a little longer to shoot than if he acts alone. He might be subconsciously looking for cues from other members, or might not be fully prepared, because he's not expecting an attack against a group. If you give up the cash, though, they're more likely to commit violence against you afterwards, because they have safety in numbers and little to lose. However, if you defend yourself and you get one or two of them running, the rest are likely to follow. They'll all follow each other like frightened birds. A single person or two people will react more quickly to an initial attack, but be more likely to just run away afterwards.
So, while it sounds counterintuitive, it probably pays to fight back against a gang, but you might want to weigh your options when it comes to one or two people. If a single guy robbed me, and he seemed experienced, I'd probably just give him $40 or whatever cash I've got, then be ready to defend against a parting attack. Getting killed isn't worth any amount of money.