I'm not very familiar with the history of Tekken so I can't say but Ryu is no slauch so I'm guessing it would be a very even match and considering that in third strike ryu has surpassed his evil side and become a master I would go more with Ryu.
I'm the same with street fighter but I know enough from friends and stuff. But Jin is pretty impressive himself. One thing I thing Jin has over ryu is that he's killed most of the big bad guys all by himself as where ryu needed help (bison and gill) and Jin took control of the devil gene faster than ryu to control his evil or whatever it's called (sorry I'm not a SF fan) but im sure ryu has somethings over jin too
Probably, and to my knowledge Ryu did not beat Gill, I think it was Alex, and if you want to go by the movie then yea, he had help to beat bison but he was still starting out, by the time of third strike he has already become a master so he would probably be stronger than them both already and killing is not part of his personality, he lets them live so they can fight so in a way, if they get stronger then he himself will be stronger by beating them where as Jin kills his opponents and has to wait for another strong opponent which would slow his growth, but that is just me speculating, it could be the complete opposite.