Is this sentence correct?Many of the captives died by suffication, disease, and infection. or replacying "by" with "from"?

First of all, you spelled "suffication" incorrectly. It's
spelled "suffocation". "Of" is the appropriate preposition to use here. "By" has to do
with proximity, while "from" is most often used to indicate original locations or
starting points. One use for the preposition "of" is to indicate cause. In the case of
your sentence, the cause is death.