Why does ponyboy insist that johnny is not dead?

In the novel The Outsiders by S.E. Hinton, it is Ponyboy, not Johnny, who is fighting for his life while in the hospital. After the rumble, Ponyboy, Johnny, and Dallas hide out in an abandoned church. However, the church soon catches on fire while the boys are sleeping inside. Johnny heroically goes back in to try and save more children from the flaming building but suffers severe burns as a result. Unfortunately, Johnny does not survive his injuries and passes away in the hospital.