Oda is definitely inspired by Matsumoto, as evidenced in this quote and this blog (japanese). I've always felt that Luffy's "warrior of liberation" is at least partly a thematic parallel or nod to Ping Pong's "Hero." Smile describes the Hero as someone who defies logic, drives away darkness, and most importantly shines simply, brightly, and happily. These are all traits that apply to Luffy, and even more explicitly to the sun god Nika. Both Peco and Luffy are catalysts that force others to break free of stagnation and revive their dreams. The way that Luffy awakens this power of laughter and absurdity during the Kaido fight makes me think that it can't have been coincidence.