My best friend being trapped??

I have a close friend who was seeing this girl. And by “seeing” I mean, having sex w every now & then. I don’t judge him because he’s like a brother to me so whatever. He was seeing a girl on & off for about 4 years but she lived in a different state. While he was seeing her he was sleeping w a girl that lived closer to him. The girl from the different state, we’ll call her “Jay.” Jay moved in w him because he got into some trouble so she took care of him. They lived together for about 6 months & she moved back. A month later he followed her. He then went back for work & ended up sleeping w the girl in his state, we’ll call her, “Kora.” Jay ends up finding out he was sleeping w Kora & trips out. Jay messages Kora telling her that they’ve been together for months now & been seeing each other for years. Kora never replies. Then, out of nowhere she hits him up & says she’s pregnant for him. He’s freaking out now saying he doesn’t understand because he’s been sleeping w Jay & she’s not pregnant, they haven’t used protection for awhile now. And all of a sudden Kora is pregnant?? He doesn’t know if he should believe Kora on being pregnant or the child even being his. His relationship with Jay is at its best right now & he doesn’t want to ruin it w Kora’s claim. I honestly don’t know what to tell him. So I’m hoping to get some feedback of what I should say to him or something.. thanks!