My question is, if your ex has let her current husband adopt the child you had with your ex, would you.. being the father still have to pay child support?

No. By law the child support would end, unless there is something in the adoption papers. Why do you ask? Is the ex wife still asking for child support?

Well a friend of mine who was married to this girl, her current husband wants to adopt hers and my friends daughter. So I was just curious if he will still have to pay child support

Okay, if the biological father has no objects to the adoption and signs his rights away, then I cannot see how he would still be liable for child support. Now if he still wanted to buy things for his daughter, that is his business.