If you rely on history and believe history will repeat itself, then the bitcoin price increase is related to the halving and it is the main catalyst. But to say that the block reward halving is the only factor driving bitcoin's upside momentum, I don't think so. The value of bitcoin depends on a lot of factors, not just a limited supply. So if in case we don't have a bull run after the halving, I believe that in the more distant future bitcoin will also increase in price as demand for it increases.