Recently I came across an discussion on Twitter that revolved aroud the topic, and I would like to remember an when people bring up "The Birth of a Nation" and how that 3 hour hate speech ressurected the KKK, it is "Fiction can absolutely influence reality, but it can't be done alone, it has several external factors that helped "The Birth of a Nation" have the impact it did, like the Jim Crow laws still existing at the time and the president of the USA endorsing the movie.
The NSFW tag because the article does contain NSFW images