If a 7/2 off-suit faced off against a 6/2 off-suit, the possible outcomes would be as follows, according to my Texas Hold ’Em Calculator.
7/2 wins: 57.07%
6/2 wins: 25.13%
Tie: 17.80%
However that doesn’t prove that 7/2 is the superior hand in general. Considering only your own hand, according to my various power rating tables, 7/2 off-suit is worse than 6/2 off-suit. For four or fewer players, the worst hand is 3/2 off-suit.
So, if the bet was phrased as who would win between 6/2 and 7/2 offsuit, then you win. However that doesn’t prove that 7/2 is the better hand in general, only for that one situation.