How do Lions survive in the winter ?

They do very well in the winter. It isn't like it's really cold where they are, so plants don't die and the plant eaters (on which they prey) don't disappear. What actually happens throughout most of the range of the lion is that "winter" means the rainy season. At this time, just about all their range is green with vegetation. The zebra and the antelope and other critters on which they depend for food are spread out and eating well, and the lions are hunting them. Life is good.
During the "summer" when it is hot and dry, the big herbivores, which were "all over" during the rainy season, are confined to places where there is water. And the plants have been baked down to dry stalks everywhere. The plant eaters are having a tough time, and so are the lions. The range of these plant eaters has shrunk dramatically because they need to be near water. But though the lions don't have to look far to find them, they do have to compete with other animals for water. Lions can die of thurst as easily as any other animal. In the winter, it is raining, and with the resurgence of the plants, the plant eaters spread out to graze, and the lions move with them. It is "easier" for the lion in the "winter" because it can generally hook up some food, and it doesn't have to search for water. The hot, dry "summer" beats the lion down, just like it hammers all the other animals.