Yeah, to quote, "Crona is presented throughout the series as having an ambiguous sex, and although hints are given to identify the gender in both the anime and manga, nothing has ever stated it exactly." & "In the English dub of the anime, male pronouns are used to refer to Crona, but this does not mean Crona is male. Funimation admitted that he/she had to settle with this rule because he/she felt that "it" would have been insulting to Crona as a character. The same rule applies to the Yen Press translation of the manga."
Even the mangaka himself doesn't know Crona's gender, as he hasn't settled on one yet.