Importance of QUANT score on GRE for math grad school
In the US, at least, no single thing is likely to knock you out of contention. Aim high, but don't put all of your eggs into too few baskets. The competition is fierce, of course, in top level schools, but if you put together a good application that clearly predicts success you should come out well. But, make sure that you have very strong letters of recommendation from people who can speak both of your past success and your likelihood of future "wins". How hard you work, how serious you are, etc. 

I suppose there are a few places that might have a cut-off score, but not everywhere you might want to go would do that. It is rather foolish in any case.