This would be refered a neice yes it does not matter the relatinship like step neice if he is related in a marriage the that's his niece.
Your niece in law.
Your brother or sister's daughter is called 'your niece.'
Your niece in-law, or your niece by marriage.
Your brothers ( or sisters ) daughter is your ( niece )
The daughter of your husband's brother is his (and your) niece. Her daughter is his (and your) great niece.
The daughter of your husband's brother is his (and your) niece. Her daughter is his (and your) great niece.
Your sister's daughter is your niece. Your niece's husband is not related to you.
If she is your sisters daughter then she is your neice :)
Your niece's husband's daughter is also your niece's daughter and therefore she is your great niece. You are her great aunt or great uncle, depending on your sex. If your niece's husband's daughter is from a previous marriage, and so not also your niece's daughter, you are not related to her. Of course, if your niece adopts her, then she is your adopted great niece. If your niece married her husband while his daughter was very young and everyone has been treating her as your niece's daughter, then you can call her your great niece if you want, but that does not change the fact that you have no common ancestors and therefore are not related to each other.
She is your niece.
Your sister-in-law's husband may be your brother. If so then the brother-in-law is either your husband, in which case the daughter is your daughter; or the brother-in-law is your brother, so the daughter is your niece or the brother-in-law is the brother of another sibling's spouse, in which case the daughter is still your niece If your sister-in-law's husband is not your brother, then he is not related to you and his brother-in-law's daughter is not related to you.
Your sister's husband's sister's daughter might be called your brother-in-law's niece, although that is less specific than calling her your brother-in-law's sister's daughter. There is no term in the English language for a relationship between you and that person. You are not considered to be related.