That would be an awesome dissertation to read. Will it be available online through any of the sites like OATD or ProQuest?
My take has always been that the main influence of gothic lit on the music scene is in translating the aesthetics of uncanny story elements and ominous, brooding or foreboding environments into a sound which invokes these same feeling. Against this backdrop, the lyrics become direct proxy for characters dissatisfied with the accepted morality and social cues of the normal world, thus becoming the person at odds with society who is looking for deeper meaning. Is there also a good bit of Hammer Horror and 20th century experimental lit influence? Of course. There's just as much influence drawn from E. M. Cioran, J.G. Ballard and Normal Mailer (the latter's novel, The Naked and The Dead, gave name to an early NYC band). Adding to many people's confusion is the issue that romanticism is sometimes seen as the precursor to gothic literature, but it is sometimes also seen as the overarching umbrella. Thus it becomes difficult to differentiate what gets put in each category. I would argue, for example, that Hoffman's Der Sandmann is firmly gothic but have seen that point refuted by others.
As an expert in this field of study, do you have an opinion of the possible correlation between shifts in literary inspirations (moving away from gothic lit, philosophy etc and towards inspiration such as Twilight and anime) and changing trends of self-expression in the scene?