The analysis of the quote is fairly direct. It seems to suggest that one must make use of the time that one has. One must "live life," as it were. Through Night, I tend to think that Wiesel has some complex thoughts about such a sentiment. While Wiesel would affirm the basic sentiment of life that echoes in the sentiment, testament to his own survival, I think that he would suggest that the true horror of the Holocaust is the dehumanization of individuals to the point where their own spirit of living was absent. Eliezer is driven to survive, even if this means cutting off all connection between he and others. The idea of "what you do with the time you have" is undercut significantly when the perpetrators of abuse reduce individuals to being nothing more than animals whose survival is all that matters.
Wiesel depicts situations that would repudiate the notion that if individuals simply "live life," their function as human beings is accomplished. Consider the case of the father who steals extra bread for his son, only to find that his son ends up beating up the father for the bread by telling the other prisoners on the train about it. After his son gets the extra ration of bread, the prisoners turn on the boy, pulverizing him and throwing the corpses of father and son out of the train. Consider the case of the son who abandons his father so that he can live. Consider the case of Eliezer who listens to his father begging for life, calling out for his son, and does not do anything to help him. These are situations where the true terror of the Holocaust is the reduction of human beings to nothing more than creatures where survival is all that matters. In this condition, "what you do with the time you have" is undercut by the need to survive. This condition severs bonds between individuals and even removes the bonds that individuals have with their own desire for a better life. It is here where I think that Wiesel might suggest that the simplistic notion of the quote has to be reevaluated in the complexity that is the Holocaust.