I haven't had an unplanned pregnancy, so you can take my opinion as you like.

I think that a "man" who gets a girl pregnant, and then threatens to leave her if she won't terminate is not someone she should be with anyways. Sex makes babies. That's a fact he has known for years. He was no doubt willing to have sex, but is now unwilling to take responsibility for his actions, and the child he has fathered. If he says he'll leave her if she won't end the pregnancy, then she will be better off without him. Pregnancy or no pregnancy, a man who will leave you when you need him most is not someone you want to be in a relationship with. And, since you've said she doesn't want to terminate, she will most likely resent him for making her do it, and regret the decision for her whole life, whether she remains in a relationship with him or not.

Encourage her to look for other support. She needs her family and friends to tell her they'll be there for her. There are crisis pregnancy centers that can also provide assistance. Her DF may or may not come around, but he sure doesn't sound like a guy you'd want to build a future with.

All the best to her!