By "how attractive you are", do you mean looks-wise?
For me, and a lot of other girls, attraction is a whole package. If you just mean looks-wise, I'd have to say, no, how many people fancy you does not automatically indicate that you are hot or not.
You also need to define "interest". What does he mean by "girls have been interested in him"? Have they personally come up to him to confess their feelings? Or has it just been what he thought because they flirted with him?
A lot of girls are old-fashioned and think the guy should approach them, or are shy and prefer for the guy to approach them because they are afraid of rejection. You having to approach girls doesn't mean they didn't like you to begin with.
...I'm just wondering whether you were on the same page with this.
At the end of the day, the truth is, the 'hotter' people are going to have an easier time of getting dates...so maybe your friend is indeed 'more attractive' than you. Doesn't matter much though. Like I said, attraction is a whole package. There are redeeming qualities in even the ugliest people....and looks can only take a person so far. They don't make a meaningful relationship last.
As for myself...I'm a girl, and I think it's easier for us because men are more likely to approach us, but I've had...oh...11 people?...pursue me in the last two years....in terms of people I knew and saw every day.
In truth, it doesn't really help my confidence becuase I have huge guilt problems and I end up just feeling really guilty for not liking them back.
It's nice, though, if they are people I like back. That helps my confidence, but only until things go sour.