Well his son made hundreds of millions / billions from selling directly oil from ISIS held lands, since nobody else wanted to deal with them. His daughter personally built and supervised hospitals in Turkey specifically built to treat wounded ISIS fighters. These are verified public informations, although they obviously deny it.

Erdogan is as much pro-ISIS as one can be. Maybe just a political game during complex conflict to fight against US-supported kurds at all costs, maybe not. We don't know.