What happens to Fortunato at the end of "The Cask of Amontillado"?

The end of "The Cask of Amontillado" is a little ambiguous. It is not quite clear whether Fortunato is dead or stubbornly remaining silent. 

“For the love of God, Montresor!”

“Yes,” I said, “for the love of God!”

But to these words I hearkened in vain for a reply. I grew impatient. I called aloud—

“Fortunato!”

No answer. I called again—

“Fortunato!”

No answer still. I thrust a torch through the remaining aperture and let it fall within. There came forth in return only a jingling of the bells. 

It seems unlikely that Fortunato could have died of fright. More likely, he has just given up trying to escape from his tight chains and is resigned to his fate. The jingling of the bells on his cap suggests he is still alive in there. He might have remained alive for days or weeks. He would not die of thirst because there was plenty of water dripping along the granite wall. He could have licked the wall to assuage his thirst. He was more likely to have died of starvation. There may have been just enough oxygen in his crypt to allow him to breathe.

If Fortunato remained alive for several weeks, he must have suffered terrible mental torture. He may have imagined he heard footsteps coming outside the stone wall. He might hope searchers would rescue him, or that Montresor had relented and was coming back. Edgar Allan Poe leaves the rest of the story up to the reader's imagination. One way or another, Fortunato died in his chains.

For the half of a century no mortal has disturbed them. In pace requiescat!