This question presupposes that we understand what is meant by "masculine."

However, before getting into that, one element that can be seen as masculine is the absence of any female characters in this tale. This is a story of two men.

Second, if we understand traditional male thinking as hierarchical, with men organizing themselves according to rank and assigning one male "top dog" status, then we can understand Montresor as using his wiles to assert a superior position. This would differ from what is commonly understood as the more communal way of social organizing based on compromise that is often associated with women.

Feeling competitive and having to "win" is also a trait commonly associated with masculinity, as is defending one's honor in patriarchal cultures. Montresor feels he has been insulted; his honor has been attacked. In his traditional Italian culture, it might be all-important for him to protect his masculinity from this sense of dishonor, and this might justify his murder of Fortunato in his own mind.