Here is the passage to which you are referring.  The last sentence of this passage is the last sentence in the story:

• He felt vaguely that his whole life was determined by the bingo wheel; not only that which would happen now that he was at last before it, but all that had gone before, since his birth, and his mother's birth and the birth of his father. It had always been there, even though he had not been aware of it, handing out the unlucky cards and numbers of his days.

The pronoun "it" that starts the last sentence refers back to the bingo wheel.  The author, and the narrator, are using the wheel as a metaphor for how the protagonist feels about his life.  The bingo wheel represents fate - every life is a turn on the wheel, and there is no telling where the wheel with stop, and therefore, what will happen with the life.  The protagonist feels trapped by his fate and out of control - the wheel has spewed out unlucky numbers for him and he is suffering the consequences of things he can not control.