Poe uses death and the process of decay, which is a Gothic element and these topics are one of the most prominent themes in Gothic literature. Almost in all of his tales, one of the characters dies or is mourned.
Madness is another Gothic element Poe refers to. The theme appears in almost all of his famous short stories including The Tell Tale Heart and The Cask of Amontillado.
Additionally, most of Poe's stories take place in dark and haunted places. It is peculiarity of Gothic stories.