My sister is pregnant and the father doesn't want the baby. If he gives up his rights, does he still have to pay child support? Also, does he have the right to see the child if he gives up his rights?

First of course he can not just "give up his rights". Next if he wants to try, first they have to wait till the baby is born, he will have to hire an attorney to file a motion with the court to allow him to terminate his parential rights, almost no court will allow this just becaue he does not want to be the father.

Also if he does give up his rights, unless it is to allow someone else to adopt, he will have to pay child support.

If he was allowed to give up his rights
( which he will not be allowed) he would not have right to see the children

There are hundreds of threads in this forum with the same question. There is a sticky note at the top of the forum that answers this question.

Bottonline, a court will only grant a TPR to clear the way for an adoption or where the parent is a danger to the child.

So the father's thinking he can just give up his rights doesn't know the reality.

I personally was adopted when I was eight years old. My biological mother had to sign away her rights to my sister and I, so she could keep the youngest two children. Now, having gone through that, it was the only good thing my biological mother did for me and my sister. If he's set on giving up his rights, I wouldn't fight it. It's either that, or years of trying to get child support and dealing with a dead beat dad. And no, he wouldn't have rights to see the child. My biological mother can't see my sister or I without consent from us. I'm not sure if this helps.