is he really that influential?.... is he really the pre-eminent string theorist

 

how do other top notch theorists like sylvester gates, nathan seiberg, and juan maldacena etc.etc. compare to him

is he really that influential?.... is he really the pre-eminent string theorist

I think he has been very influential and has written something about just about every topic in modern theoretical physics. His main power is in seeing the physical relevance of mathematics.

 

He was the first to see in importance of branes in string theory and that has opened up a whole new understanding of strings.

 

He has found important links between mathematics, usually in the form of algebraic geometry and string theory. For example you should look up the Gromov–Witten invariant and symplectic field theory.

how do other top notch theorists like sylvester gates, nathan seiberg, and juan maldacena etc.etc. compare to him

Gates was one of the first to explore supersymmetry. His work that I know of is to do with representations of supersymmetry. It gets technical quickly so I am not sure what to say next...

 

Seiberg has been very influential, his work includes topics like S-duality, d=4 N=2 supersymmetric gauge theories (along side Witten, look up Seiberg–Witten invariants ) and the emergence on noncommutative geometry from string theory.

 

Maldacena is best know as the originator of the AdS/CFT correspondence, which has been put to good use by many other people. So I would say he has been very influential also.