1 person is tough enough to deal with, 2 people can be delt with depending on your mindset, and how you have been training, 3 or more and your gonna need an equalizer (impact weapon, blade etc) It really depends upon your attackers and how tough they really are compared to you! Trust me, if your outright beating 5 or 6 guys empty handed, its because they just dont want you bad enough!
Also, expect to get hurt unless you have a firearrm and are at a safe range! Believe me when i say you do not want to have to contend with multiple attackers empty handed, no matter who you are!
Awareness is your best friend, not putting yourself in the situation to begin with, or getting out of the situation as quickly as possible! Talk your way out, beg, lie, cheat, run, its not like Seagal movies, i promise you will get hurt!
That being said, if for whatever reason you were to find yourself in the worst of situations, you must be willing to do whatever is necessary just to be able to crawl away! Lets say that you just couldn't avoid the attack. your best bet is to move laterally, to stack your opponents so they cannot surround you, and do everything that you can to stay on your feet! Trying to go toe to toe with one person will always open you up to the sucker punch from one of the others! You fight dirty, like you have never fought before, hairpulling, eyegoudges, biting, groinshots, anything goes, if you have a weapon of any kind, use it! Attacking the weak link or the leader is best when the pack is just forming, youll know when they are egging each other on and trying to get the courage to move. Also, if you have a weapon, use it on the run to escape, if you stand still its over!
In the end you are going to have to tap that primal part of yourself, that bear that sleeps within us all, and has helped man and woman survive from the beginning! Its a scary place to go, you may do things you didnt think you could or would do, cuz if ya dont, well then ya neaither live nor win.
I do think that you should train for this to better help your chances of surviving an attack if you were to ever find yourself in such a situation. The thing is, you must train realisticly, with resistance and weapons, against people that are fighting you back with no prearranged scenerios! The most important thing is that you must develope a winning mindset, and a willingness to go beyond what your self imposed limitations may be! Even with all that, it only gives you half a chance, the other half depends on whos attacking you, and what the gods have decided on that particular day
Train for it, but do everything in your power to never let it happen!