Specifcally in terms of Hawking it is a bit hard to look past the King Arthur comparisons, i find the actual tactical discussions and how the battles are managed to have clearer traces.
A lot of what Mat quotes when discussing war and a general's place in it is extremely similar to Clausewitz or Machiavelli (although Mat is extremely ANTI-Machiavellian in areas other than war of course), the insistence that a general that leads the charge has surrendered his baton and the capability to lead and the very strong insistence on adaptability for example. his invention of cannons too and his instruction on their uses. The incredible value Mat places on speed and his desired results are very 'Blitzkrieg'-ish too...various considerations around scouting and logistics...but so much has become general knowledge it could have also all so easily been incidental. The cannon thing makes me think the closest historical figure to Mat in terms of war is Napoleon, who was an expert in use of cannon and especially 'defeat in detail' which Mat is arguably the absolute best in (not even mentioning them both being preeminent tacticians and generals of course).
...also OP Genghis Khan did not create the largest empire in history, that would be the British Empire.