In short, Pavel dies from Lieutenant Kotler’s beatings after Pavel spills wine on Kotler during a dinner with the commander of the camp and the commander's family.

In chapter 13 of The Boy with the Striped Pajamas, by John Boyne, Pavel serves as a waiter and vegetable chopper in the house of Bruno’s father, the commander of the camp. Pavel was a doctor before he was imprisoned in the camp, which Bruno found out one day when he fell, and Pavel was the adult who took care of him. Pavel is very smart, but he is Jewish, so we know he is not respected, cared for, or liked by the Nazis. Bruno describes Pavel as very old, having grey hair, and stooping over. Pavel is an older man who is not in good health. Bruno describes him at the dinner as standing there almost looking like he is asleep, with no life to his eyes and a slow response time. He also discusses how Pavel is becoming smaller each week, has shaking hands, and is steadying himself against the wall. These descriptions allow the reader to see just how weak Pavel is.

Considering Pavel's weakened state and Lieutenant Kotler’s anger toward him after the spilling of the wine, it likely wouldn’t be difficult for Kotler to kill Pavel when he is beating him. The reader can assume that Pavel is beaten, because Bruno is very upset about the situation and the fact that his father hasn't stopped it. He cries, and his sister goes pale. Although Bruno doesn’t ever directly state that Pavel dies, he does say Pavel is replaced by another Jewish man, and as Shmuel said earlier when they were talking through the fence, the Nazis are not concerned with the Jews getting better, so Pavel wouldn’t get medical help for his injuries. Through these pieces of the text, it can be assumed that Pavel dies after being angrily beaten by Kotler.

Did Pavel die in The Boy in the Striped Pajamas?

In The Boy in the Striped Pajamas, Pavel works as a kitchen helper and server at Bruno's house.

The text describes Pavel as an old man. To Bruno, Pavel looks to be older than his father (the Commandant of Out-With).

As the story progresses, we learn that Pavel was a doctor before he came to Out-With. In Bruno's home, Pavel works in the kitchen peeling vegetables for dinner. During dinner each day, the old man puts on a white jacket and serves Bruno's family at the table.

In chapter 13, Bruno notices that Pavel seems to have grown "smaller and smaller each week, if such a thing were possible..." The description of Pavel's physical condition tells us of the suffering he has endured.

During dinner, Pavel appears subdued and sad. In between serving the family, he stands near the wall and waits until he is called. Bruno is uneasy as he watches Pavel. He notes that his mother had to ask for soup twice before Pavel responds.

Later, Bruno's father complains that he had to ask for his wine glass to be filled four times. Bruno can tell that Pavel is struggling to fulfill his duties. Unfortunately, matters deteriorate when Pavel accidentally spills wine onto Lieutenant Kotler's lap.

The text tells us that the Lieutenant's reaction is both "unexpected" and "extremely unpleasant." Yet despite the Lieutenant's actions, no one stops him. We learn that Bruno cries, and Greta grows pale at the spectacle.

And while Bruno realized that Father was generally a very kind and thoughtful man, it hardly seemed fair or right that no one had stopped Lieutenant Kotler getting so angry at Pavel, and if that was the kind of thing that went on at Out-With then he'd better not disagree with anyone any more about anything; in fact, he would do well to keep his mouth shut and cause no chaos at all.

By all indications, Lieutenant Kotler meted out extreme physical punishment on Pavel, and the frail old man died from his wounds. After chapter 13, Pavel is heard from no more, and this further reinforces this verdict about his fate.