The kite work
The job of the father on the boat is to report the weather to the crew below. He does this by literally flying a kite to show a manifestation of the wind. A way to interpret this symbol might be to take the kite as the father's ability to discern, and the harsh reality of nature represents itself. The father survives the storm by paying attention to the kite and by enduring the harsh realities of nature—until they overcome him. But his approach was basically correct, so the son chooses to do the same.
The Jade Circus
One way of interpreting the plot might be to say that the Jade Circus represents the reward of enlightenment. Suppose that the novel is a metaphor for a good, mindful, dutiful life—the Jade Circus represents the admiration of others, the platform to put good energies into the world through entertainment, and all done to the glory of the human race. The reward for the enlightened, well-adjusted man is high esteem in a beautiful world of humans. The reward is not money or status, but honor.
Uncle Bo
This slothful individual represents the corruption of integrity and character, and the end result of a life made by compromising ethics for expedience. He doesn't have the self control to be successful in the world, so his addiction to pleasure runs the show, at the expense of innocent victims, by the way.
The motif of vice
Di Chou is a violent alcoholic who feels bitter resent toward other people. He's offended by honorable people. Uncle Bo doesn't have the spine to keep himself from gambling the family's income away. The implication of this motif is clear. There is an honorable way to approach life, the hard path of the suffering servant, and there is the path of least resistance, but the second, compromised path is only a trap that leads to one's powerlessness to resist temptation, and ultimately, the development of moral corruption.
The final escape as an allegory
Look at the last scene. A couple important things to notice: The Uncle uses a demonstration of violence to get what he wants from the young men. He uses intimidation. He wants them to know that if they fail to give him what he wants, that he'll take it from them by force.
The boys survive, though, by non-violent means. They don't stay, and they certainly don't buckle to the uncle's intimidation tactics. They merely leave in the night. That interpretation would make this an allegory for pacifism.
