What are some literary elements in "The Bet" by Anton Chekhov?
The phrase "literary elements" seems to be rather vague and all-encompassing. You might benefit from re-reading the story and trying to narrow down your terms of reference somewhat, as clearly every work of fiction has a number of "literary elements" that could be commented upon. One way to approach this question, however, would be to talk about the difference between the two central characters, the lawyer and the banker, and the way that these characters are shown to develop and evolve through the experiences narrated in the story.
Let us begin by considering the lawyer. Having made such an impetuous bet, the lawyer, by the end of the story, is shown to have developed and matured immeasurably. His final note, which renounces the money he was due to win, gives ample evidence of the way that he has transcended so many of the earthly problems and issues that still dog the banker:
You have lost your reason and taken the wrong path. You have taken lies for truth and hideousness for beauty.
Clearly such statements indicate the extent of the lawyer's development. By contrast, although the banker is moved to tears by reading the lawyer's note, he still contradicts such an action by the way that he carefully places the lawyer's letter in his safe. In contrast to the lawyer, the banker is clearly shown not to have evolved beyond his greed and self-interest.
Thus one literary element you could helpfully focus on is that of characterisation and the way that it is used to compare and contrast these two central characters.