The sentence is : まあ 何人来ようが || どうってこともないがな... (|| = Column break.) It doesn't matter how many people want to come... I'm not sure whether the first が is the subject particle (and ...
I did a quick search on this site to see if I could find any answer to this and found this question: Does the volitional form of a verb mean both "lets" and "I want to"? But ...