YES HE DID DIE
Why?
Have you finished it already? This might come out as a spoiler
Anyway, he was burned in the fire and then was sent to a hospital. He could have survived though. He called out to yoonbum everyday and when a grandmother who stayed in the room beside him (or near) heard his cries everyday and all the time, she finally had enough and she decides to suffocate him with a pillow to shut him up.
It's okay tell me
Sangwoo ends up dying after being burned because a grandma suffocated him to death with a pillow because he was "too loud" He called out to Yoonbum every time and she finally had it. It's kinda sad because Sangwoo's mother had also tried to suffocate him through a pillow when he was a child.
???????