I'll add, that copyright can only dissipate after the death of the original author. The exact number of years is different depending on the country, but after that point it enters what is considered "public domain". The Sherlock Holmes stories for example are public domain, so anyone can make a movie or write their own book using those characters or stories.
On top of that is publishing rights, which can last in perpetuity (forever). So even in 100 years, you won't be able to distribute gay porn made today if the publishing rights are still in effect. You can do whatever you want with the characters in the porn though!