The first basis for any pronunciation is its origin and/or history, but names in the USA are not so constrained.
1. In American English, "c," when followed by an "i," is usually soft (like "s"), not hard (like "k"). Though names may be an exception, be prepared to correct people a lot.
2. The "sh" reading of "ci" comes from an Latin/Italian interpretation of the phoneme, as in "fas
cia."
"Like arrows in the hands of a warrior are sons born in one's youth." Ps. 127:4
JoHannah Jubilee, BenJudah Gabriel, Aaron Josiah, Jordan Uriah,
Maranatha Nissiah, (Anastasia Nike, 1992-1992), Jeshua David,
Shiloh Joshana, Elijah Daniel, Hezekiah Nathaniel, Zephaniah Joseph