Salvation
Jsiah is a modern phonetic spelling variant of the Hebrew name Josiah. It derives from the Hebrew name Yoshiyahu, meaning 'Yahweh supports' or 'God is salvation', famously borne by a righteous king of Judah in the Old Testament.
Less common today
Jsiah isn't in the latest US Top 1000. It last peaked at #7,077 in 2016.
US births per 5-year period, 1990βpresent (SSA data).