In the case when the average GPA is high, how would this affect my chances to say get into T14?
I might be wrong, but isn't this where the LSAC weighted GPA comes into play? LSAC will adjust your GPA based on major, difficulty of coursework, institutional standards, etc. Usually it doesn't go up or down too much, but I think this exact issue is part of what LSAC is trying to compensate for.
Without knowing what your GPA is it's impossible to gauge your chances, but as SoCalLawGuy said you'll probably need at least a 3.5-3.6 to have a shot at the T14.
Or could I balance it out with a high LSAT?
You can almost always compensate with a high LSAT, depending on what school you're applying to. At the most elite schools a high GPA and high LSAT are required. They have so many highly qualified applicants that there isn't any incentive to accept someone with lower numbers. Outside of the elite schools (Harvard, Yale, Stanford, Columbia, etc.), a very
high LSAT might
make up for a lower GPA. Depending on your GPA, a score of 170+ might get you into a few other highly regarded schools.
There are also plenty of great schools outside of the T14 that might suit your purposes just as well. Make sure to check out those options, too. Until you have an LSAC GPA and a live LSAT score, however, everything is speculation.