I knew that Jin Yong and Liang Yusheng were friends and interacted, but according to this part of a profile of Gu Long, it looks like he hung out with Jin Yong and Ngai Hong, at least a little bit:
http://koolung.tripod.com/extra.html
Does anyone have any idea how much exposure they would have had to each other's writing at different stages? By 1960 Jin Yong already had a movie out (http://www.imdb.com/title/tt0201121/), but Gu Long was just writing his first book off in Taiwan. Jin Yong was publishing in a newspaper, which even if it sometimes meant a small circulation (some things indicates that initially it might have been quite modest in its readership), at least he did have an automatic audience, so could start getting known right away. Conversely, it seems it is harder to go from being an unknown author to getting a famous book as quickly.
My largely ignorant perception is that Gu Long didn't start getting famous until the late 60's, just about the time Jin Yong was finishing up his initial writings, ending in 1970 before spending rest of the time doing rewriting, so timewise it might have been difficult for GL to influence JY's writing. Unfortunately, I can find very little in depth biographical information on GL in English. I'd like to learn a bit more about his background and influences. It sounds like he might have majored in English and/or other European languages in school, so that is how he got such an access to foreign styles of writing and influenced by things like English mystery and adventure novels.
Conversely, there are two books on literary criticism on JY in English that also have a lot of history and background (The Jin Yong Phenomenon which is a compilation of essays edited by Ann Huss and Paper Swordsmen by John Hamm). Gu Long is only mentioned in passing in each of these books. In the Jin Yong Phenomenon though there is an interesting passage comparing GL & JY. The author of the essay, Cheng Pingyuan is talking about genre boundaries and incorporation of different influences on wuxia fiction and he writes:
The fact that martial arts novels adopt multiple components from different genres places enormous demands on the breadth and depth of knowledge of the author. Gu Long succeeds by personal genius, but Jin Yong is the only "authentic" (mingmen zhengpai) martial arts novelist.
I have no idea what mingmen zhengpai means. It is "upright door" literally? Some expression for being solidly representative of something?
Basically he goes on to talk about how Jin Yong knew (knows I guess is more proper) more about history than any other wuxia writer (lectured on it, eventually got a PhD from Cambridge in it, etc.), which obviously was hugely influential in his writing. However, nothing more is said about Gu Long and his influences.