I doubt he would have had any significant influence. Jiang Wei was only a minor officer when he left Wei, and Wei had a heapload of talents to choose from. Plus Jiang Wei isn't that great to begin with.
AHHHHH thats not true lol Jiang Wei could have done alot better if zhuge would have not died. I mean think about it.... all of the knowledge he had obtained from being with zhuge... if only zhuge could have lived. The way I see it is like this...
Zhuge Liang was the #1 smartest man ( remember this is my veiw so please lets not debate over the smartest person) from the 3k era. If I where to trust anyone's judgement it would be his. Jiang Wei wasnt a normal general. He learned as much as he could and trained as much as he could. the one thing that i hate about this world is suicied so i didnt like that about him. Any way the point is that there is no general who is "not that great" all of them fought, learned, and accomplished few to many goals. If zhuge didnt die then maybe things would have been different for jiang wei.
Any ways to answer the question. If Jiang Wei would have stayed with Wei he would have never even came close to reaching his full potintial. Wei looked at him as a piece of crud. I dont know about all of u but id hate that. I belive everything that Jiang Wei did was right execept killing his self. Jiang Wei would have not been half the great man he was if it was not for his disision to join shu. I believe that verything happens for a reason and that happened as it should have.... wow did i type all of that lol.
When the lights out.. its less dangerous.. here we are now.. entertain us