This story is narrated from a first-person objective point of view. This means that the narrator uses first-person pronouns like I or we and that he is a participant in the events that occur. It also means that he is narrating events after they have already taken place rather than while they are taking place; you can tell this, in part, because he uses past tense verbs like had rather than has and did rather than does. At the very end of the story, the narrator reveals that it has actually been "half of a century" since these events took place—a full fifty years—so he has had plenty of time to reflect on what happened and, perhaps, even justify his actions further or consider how he wants to tell his story. This point of view certainly helps to shape the action and pacing, because the narrator is more measured and less emotional than a first-person subjective narrator, who tells the story as it's happening, would be.
In addition, because of the narrator's point of view, he is able to include a great deal of dramatic irony in the text, building suspense and increasing the tension the reader feels. He tells us, for example, how he managed to get rid of his servants by telling them that he would be gone all night and how they should stay home. He knew this would ensure their leaving as soon as he did, proving his sagacity as far as human nature as well as how thoughtful and manipulative he is. Neither his servants nor Fortunato realized his intentions or nature. He also describes the descent into the vaults in some detail, slowing the pace of the work and increasing suspense as well.