What evidence is there in the first chapter of Empire of the Sun that shows impending poverty?
Jim is privileged, and much of the suffering taking place in the world outside Shanghai is very foreign to him. He is incapable of making sense of newsreels depicting the rape of Nanking, the Blitz, and other events:
The March of Time films were more somber, in a way that appealed to Jim...he watched a burning Hurricane fall from a sky of Dornier bombers into a children's book-landscape of English meadows that he had never known.
So in a sense, while there is little evidence that Jim will experience poverty and privation due to the war effort, Ballard does foreshadow it by emphasizing just how isolated Jim is. His teenaged Jewish governess, Vera Frankel, who escaped from Eastern Europe, is an example of this. Jim teases her by asking about the size of the house where her parents live in the ghetto of Shanghai. When she tells him they live in a single room, Jim can't believe it, and asks if their room is as big as a house. Vera replies, "As big as your dressing room. James, some people are not so lucky as you."
Additionally, Jim's father is portrayed as fatalistic, listening to reports about the war and talking to James about his future, which Ballard describes as "elements of an adolescence that his father seemed to assume would never take place." The reader can clearly see that trouble is around the corner, even if Jim does not completely understand it.