Nobody is going to be able to give you an exact equation or proportion that tells you the weight or importance of GPA/LSAT relative to the other aspects of your application/potential interview. That being said, from applicants I have spoken to the general consensus if we were to rank the parts of your application from most important to least important it would be first, your LSAT score, followed by your GPA, then your personal statement/supplementary essays, then your resume/extracurricular activities(some people call these "softs"). GPA/LSAT definitely carry most of the weight, but numbers aren't necessarily everything. Interviews can be very important, for example, if you had borderline numbers for a school, an interview could be an opportunity to push yourself over the edge. At the very least, as long you're relaxed and confident in how you speak, you're more likely to have a neutral impact on your application than a negative one. Focusing on improving your LSAT skills, and then hopefully your scores, is a worthy investment. Your LSAT score is the jewel of the application so to speak, and when you take it is up to you. Meaning, if you want to take 6 months to study, even a year, go for it. I can speak from personal experience, taking the test when you're truly ready is something to take seriously.
