I replayed the game twice and have not discovered any reference to Count Dracula. Maybe because they do not want him to be an important figure in the Vampyr Universe or maybe they want him to have a big impact on future games. I feel like Dr. Reid's journey is far from over so maybe Dr. Reid will meet him in future games as a secret boss or part of a side quest.
There is a signed copy of the book "Dracula" in Lady Ashbury's mansion. Within the book is a message to Lady Ashbury from the writer of "Dracula", Bram Stoker. So Dracula the character is a work of fiction within a book. That being, i'm not sure if Count Dracula can make an appearance in the Vampyr universe. Unless of course, they make it where Count Dracula was not a work of fiction, and Bram Stoker wrote about a real vampire. I could see that happening, since there are actual vampires in the Vampyr universe.