Mike has all the best ideas !
The one thing that turned me around more than anything was the reality that I wasn't alone.
Ok, I knew for 'ever' that children were sexually abused, but there was some block in my mind that kept me from making the connection with them and me.
I thought I was a sick freak who joined in willingly, and 'they' were poor souls who'd been abused by dirty old men.
The truth is different, the perps are the sick freaks and we've all been abused.
Tell him you've been here and read some things, sometimes the 'power of suggestion' is a great way to encourage someone to do something.
If you 'tease' him with bits of information that you know will relate to him he might get curious.
But I also have to say that it's unlikely you'll ever push him into doing anything, us survivors seem to only do it when we're ready to it. Unfortunately.
But show him you care, don't pass judgement ( however hard that might be ) and he'll begin to trust you and himself and see he's not a "sick freak"