During his conversation with Charley, Willy says, "you end up worth more dead than alive." Interestingly the audience is not sure wheter he is speaking to himself, Charley, or both. The audience can also sense Willy's deep despair at this moment as Willy implies that death might be equal to or better than facing failure honestly.
It is possible that he means that, if he dies, the insurance policy will pay his family more money than he could earn for them while he's alive. Willy's words can be taken literally or metaphorically, but either way, there are strong insinuations in this line that Willy is contemplating suicide.