He survived being in the Port Mafia and Mimic. He got to live life while Oda suffered and died trying to get his revenge against Mimic for what they did the curry owner and the five orphans that Oda cared for. And since we know the type of person Ango is, he isn't as strong aa Dazai.

Does Ango Sakaguchi die?

Ango Sakaguchi (坂口 安吾, Sakaguchi Ango, October 20, 1906 – February 17, 1955) was a Japanese novelist and essayist.

Did Dazai forgive Ango?

Ango is obviously more sorry than words can express for how things turned out and his role in all of it, but Dazai is not the kind of person to forgive and forget. Even if he forgave Ango there would be no erasing what he has done, and Dazai will never be able to trust him again.