The title presents us with a question that is answered during the course of the story and also points us towards the way in which the story serves as a kind of parable, which is a short, simple story that presents us with some kind of moral lesson. Of course, the question is very careful to ask how much land a man needs, as opposed to wants. This is crucial to the understanding of the story, and is also refered to at the very end of the story in its final paragraph, which ironically answers this question:
His servant picked up the spade and dug a grave long enough for pahom to lie in, and buried him in it. Six feet from his head to his heels was all he needed.
The question is thus answered: a man only needs enough earth to be buried in, which of course ironically contrasts with the vast stretches of land that the ever-more greedy Pahom desires. This of course supports the theme of the story, which is that unchecked ambition and greed destroys people. It was Pahom's desire to secure ever-greater plots of land that directly lead to his death and made him unable to enjoy the simple pleasures of life that he had. Having the title expressed as a question thus focuses our attention as readers on the moral message of the story and also points towards the irony of how this question is answered.