Getting the interview is an important signal: the firm has already decided your application is strong enough to evaluate further. From that point, case and behavioral performance become much more important because they provide direct evidence of how you think and communicate.

That does not mean the rest of your application disappears. Interviewers may have access to your resume, and the final decision is still about the whole candidate. But you should not walk into the interview trying to compensate for your GPA in every answer.

Treat the invitation as permission to focus forward. Prepare the cases, sharpen your stories, and only discuss academics if the interviewer asks. The broader context in applying to consulting with a lower GPA can help you judge how much weight to give the issue.

Once I had the invite nobody brought up my GPA at all.

I wouldn't say fully irrelevant, but you definitely have a much bigger lever now: crush the interviews.