That is correct - in Italian, 'gi' or 'ge' is used to represent the English 'j', so Gianina is pronounced ja-NEE-na,
Gianna is JAN-a,
Giuseppe is juh-SEP-ee,
Giulia is pronounced JU-lee-a,
Gemma is pronounced JEM-a,
Genoveffa is pronounced jen-oh-VEFF-a . . . etc.
:-)