Hello, I would like help from an immigration lawyer to give me advice on how to sponsor my niece from Afghanistan who is in a life threatening situation.

Does she have a current passport? That is the first step.

I believe the only way you can sponsor your niece is if she is orphaned, under 18 and not married/in a common law relationship.
If this does not apply you still may be able to sponsor her, but I think you need to not have another family member that could also be sponsored. I'm not 100% clear on that note, however.

She also MAY be able to be sponsored as a refugee. Here is more information about that process - Sponsor a refugee

If you cannot sponsor her under the family class and she is ineligible to be sponsored as a refugee, she MAY be able to be sponsored as a skilled worker in the future. CIC currently is not accepting applications for skilled workers until probably next year.

FINALLY, she MAY be able to be nominated by a province. Every province is different, see here for requirements: Determine your eligibility – Provincial nominees