Nobody "wins" in a nuclear war. Read On the Beach by Neville Shute - written way back in 1957 for a vivid depiction. You don't need a blast to kill absolutely everyone because radiation and "nuclear winter" will accomplish that quite readily.

Here's How Bad a Nuclear War Would Actually Be

"Unfortunately, peer-reviewed research suggests that explosions, the electromagnetic pulse, and the radioactivity aren’t the worst part: a nuclear winter is caused by the black carbon smoke from the nuclear firestorms. The Hiroshima atomic bomb caused such a firestorm, but today’s hydrogen bombs are much more powerful. A large city like Moscow, with almost 50 times more people than Hiroshima, can create much more smoke, and a firestorm that sends plumes of black smoke up into the stratosphere, far above any rain clouds that would otherwise wash out the smoke. This black smoke gets heated by sunlight, lofting it like a hot air balloon for up to a decade. High-altitude jet streams are so fast that it takes only a few days for the smoke to spread across much of the northern hemisphere."