To this point, at least, Malthus's theory of population has not been accurate. Malthus believed that the world's population would tend to grow too rapidly to be sustainable. He said that the poorer people would end up without enough food and that populations would therefore crash. In other words, he posited a sort of situation in which populations are kept relatively low by the lack of food.
So far, we have not reached this point. Our technological ability to produce more and more food has so far made it possible to sustain a population much larger than Malthus imagined possible.
This is not to say that he will not some day be right. It is possible that we will run out of technological advances and our food production will stop growing. However, this has not yet happened and so Malthus appears to be incorrect.