If you witnessed a supervisor exploiting women and numerous complaints resulted in nothing, would you confront him?

Yes/no ... depends on a multitude of factors. As there are many different courses of action that can be taken, confrontation may not be the best route.

• What is the exploitation that was witnessed?
• Who were the complaints made to?
• Were the complaints ever investigated or were they dismissed? If so, why?
• etc.

Not enough information to make a properly informed opinion/decision

I don't have enough background details to firmly declare what I'd do in this situation, although I'd certainly want to act in a way that solves the problem. Would it be my supervisor, a subordinate supervisor within my scope of responsibility, or a supervisor in another organization? My relationship to the person plays a role in how I'd address it. Also, were the complaints made to him directly, or to someone else who took no visible action (chain of command, IG, EO, etc.)? That would also play a role in my decision.

Confrontation isn't the only way to address it. Especially with it being a Supervisor. Numerous complaints is intentionally vague and doesn't say what has or hasn't been done. There are multiple routes that can be taken. I would document it, report it to local military or civilian authorities depending if any laws/policies have been broken and escalate it up the chain of command or at least the EO rep for them to do so. There are multiple checks and balances in place to help address thigs like this and most of the time when they doing what they are supposed to it's because they aren't being implemented correctly, aren't provided with accurate/timely information or people are trying to game the system in some way like unethical Command influence which honestly has been getting a lot of negative press lately in the last decade with anything related to the UCMJ and Military Justice system in general.

As someone on the receiving end of this behavior (I’ll spare you the details and I don’t want to relive those times) I would certainly at a minimum document each incident that you become aware of. I started a diary when I entered active duty and found it as I was working on my disability rating. I had names and dates. Your responses remind me of Vanessa. No one sees anything, no one does anything. MST cases are finally getting attention because names and places are finding repetitive behaviors, different places, different women/men, same perpetrators. Tell me you have never witnessed something similar to this in your career. This is why those cases collected dusts and victims/survivors opted for suicide.

So glad that this Special Forces Captain and his Team Sgt wouldn't tolerate it. More @ NYT link. Also glad that this shameful situation received significant media attention at the time.

https://www.nytimes.com/2015/09/21/world/asia/us-soldiers-told-to-ignore-afghan-allies-abuse-of-boys.html

As with other answers here, the answer is, "it depends." Direct confrontation may not accomplish anything, and honestly, could make things worse. Now, if the supervisor worked for me, then I'm in a position to actually make some changes. Short of that, I may only be causing problems, especially if the supervisor then tries to take revenge on the women. There are a couple channels for reporting this sort of thing, and they may be the best approach. At least it then becomes part of the official record, and the individual's commander may also become involved.

Like a man would say and do always be a man stand up for the people that can’t

In my active duty years this was not an issue. We have very few women in roles that interacted with most combat MOS's. It wasn't until many years after I was off active duty (still in active positions in the TxNG and the USAR) that I saw the abuse happen to Commissioned Officer friends that were accused, both wrongly and on one occasion justified. I did not have the chance to intervene as I only learned of it after the fact. (but if I had been there first hand I would have politely informed the (Major) that the outward appearance was going to cause a serious issue within his command.

I already did. When I was in uniform, anyway. It was part of my job as a SH/ARC.