One could argue either position based on one's interpretation of Willy Loman's downfall. To best answer your question, I will provide reasoning that supports both choices.
Willy Loman is brought to his low point because of his dream of success. Willy always believed in the American Dream, and that if he only worked hard enough and had the right personality, he would be able to have everything he wanted in life. He pushes his sons Biff and Happy to pursue a similar classic American Dream. However, the reality is that the American Dream is no longer possible by the time Willy is old enough to have achieved it. His vision of a meritocratic world in which the good rise to the top because of their own talents is based on an illusion from the past. Therefore, one could certainly argue that Willy commits suicide because the Dream has had clung to throughout his life was never truly possible—so the only way he could "take care" of his family is to die.
On the other hand, one could say that...
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