The battle between King Porus and Alexander the Great is one that is hotly debated to this day. Who actually won, and who can be counted the victor? On paper, it looks as though Alexander the Great took the day, although the battle was costly in the number of lives that were lost.
But, after the death of Alexander the Great, the Macedonian empire was unable to maintain control of India. It reverted back to Indian power about a year after the death of Alexander. As historians debate the battle and whether Alexander indeed gained any control, the fact that he had set up a Macedonian administration shows that he did rule at least a piece of the country, if not the entire principality.
So yes, while Alexander the Great briefly held a part of India, he failed to take and keep the whole country. This alone can be used to argue that he did not, in fact, win the war against King Porus.
There were a handful of uprisings that were put down, but eventually, the Macedonian troops in the region could not maintain their presence. After the death of Alexander, his empire was carved into pieces by his generals, each taking their own control. This left areas weakened without one strong leader at the helm. While many of the generals were competent leaders, they lacked the enthusiasm and inspiration held by Alexander the Great.