I read the beginning of the first Conan story written by Howard (The Phoenix on the Sword), in the second chapter Conan speaks with two of his advisors and friends, and oh boy I felt like I was reading Robert talking to Ned.

In this chapter Conan talks about how fun and easy it is to conquer a throne and boring and hard to keep it, how much he misses fighting and having a horse between his legs. Conan said that his reign rusted his sword, and it reminded me of Donal Noye's words about Robert: "Robert was never the same after he put on that crown. Some men are like swords, made for fighting. Hang them up and they go to rust."

Conan's reign is also disrupted by some of his subjects who hate him and regret the reign of the previous king, and this reminds me of the case of Robert's reign, where quite a few of his subjects are still loyalists of Aerys.

One of his friends/advisors also says in this same chapter that Conan likes to laugh out loud and drink a lot. And Conan is a known womanizer.

George read the Howard stories in his youth, according to his own words he enjoyed reading the stories of Norse mythology because they reminded him of the stories of Tolkien and Howard, and he also said that Aegor Rivers was physically inspired by the Conan version of Robert Howard and the Conan version of Barry Windsor-Smith.

So yeah, Conan is definitely the major inspiration for Bobby B imo.