I don't have a link, but show him all the seriously creepy artwork that the Podestas had hanging in their homes. You can't look at that and not realize these are some pretty sick people.

That was my first red-pill on Pizzagate. It didn't convince me that everything alleged was real, but it definitely opened the door for me to believe there might be something to it.

Rather than overwhelm them with a ton of stuff, start with one well-documented, undeniable fact that they can't dismiss. It might be the artwork or something else, but the first acknowledgement that there might be something there is the biggest hurdle.