He is a director but more specifically, Len Riggio is the founder of Barnes and Noble. Len Riggio has deep ties to GameStop's history. Len created an entity entitled Software Etc. which was a store within a store at B.Dalton bookstores. Later, Software Etc. was spun off in an IPO which Len held a majority stake. As time passed, Software Etc. merged with Babbage's (both mall based software retailers) and formed NeoStar. NeoStar went bankrupt eventually and was purchased out of bankruptcy court by...Len Riggio. It later became Babbage's Etc. who then bought Funcoland who then bought EB.
Sooo...that's how Len acquired so many shares of GameStop. But without Len and his investors (of which current CEO Dick Fontaine and current president Dan DeMatteo were both part of), you'd have no GameStop.
Dick Fontaine(CEO), Dan DeMatteo(COO) and David Carlson (CFO) are all former Barnes and Noble executives that Len hand picked for the positions they are in now. James Kim and his wife were the former founders of EB Games which is why they have/had so many shares.
How do I know, well I worked for GameStop for 13 years through all the highs and lows. Currently enjoying the high and wishing I still worked worked there.