I'm not sure what you are asking in terms of "what form is it". It seems like a fairly straightforward spelling variation of
Janice to me. The Wikipedia page for the actress seems to say it's pronounced as "jah-NIECE" rather than "JAN-iss", so one could think of it as a blend between
Janice and names like
Denise.
https://en.wikipedia.org/wiki/Janyse_Jaud#Early_life