Rousey would literally kill you..or most any other nonprofessional male fighter. Uh, not a chance. She would have no chance against any big, powerful male. The difference in height, weight, reach, strength, power, etc., is just too great.
Her chance for a draw would be, I would not hit her, because I would not hit a woman, and because I'd be afraid of killing her if I did. So I would just wrap her up and hold her.
Read the other posts; we distinguished between just straight up boxing (which I think a bigger, stronger trained man would win) as compared to using the full bag of MMA tricks (kicks, judo, jujitzu, etc), which I believe the MMA trained female would win over the boxing only trained male.