Code Geass R2 ending: official explanation by the show staff and the anime itself

[Lelouchfan]

The show staff have OFFICIALLY CONFIRMED that LELOUCH IS DEAD. They have been repeating this for 10 years. This was confirmed in interviews, live commentaries, tweets, the official guide book, the new epilogue they made (2009), and the sequel's name is even "Lelouch of the Resurrection". (Mind you, the sequel is a single movie and not a season, and it's part of the recent movies' alternate universe, but Lelouch's fate is identical in R2 and the movies!)  

There's a Code Geass community database on reddit which gathered all the information we have, all the official statements, etc, and then goes over the code theories' points and shows how they are contradicted by the anime itself. The anime itself makes it impossible for Lelouch to have the code.
It's a long post, but any Code Geass fan will want to read it.  

As an example, here is an excerpt from "Geass Memories", a series of tweets made at the 10 year Code Geass anniversary which talked about how they made the anime 10 years earlier:

- "Before I started writing the story of a person called Lelouch, I confirmed with Taniguchi-director something. That thing was that THE END OF LELOUCH WILL BE DEATH."    
- "At least he is aware of his sins and pays for them with HIS DEATH."   
- "This man called Lelouch will pay for his sins by HIS DEATH. The story follows him till he finally make this decision."   
- "Probably this Lelouch we see in the first episode of the series wouldn't CHOOSE DEATH. He would try something to avoid it. He couldn't DIE, for Nunnally as well. But we see him changed in the last episode."   

Official source
Screenshot   
Translation  
  
Another example, this one from the official guide book which clarifies the Zero Requiem:  
- "For those two who bear the heavy sin known as killing their fathers, they share the belief that they can forgive each other by imposing the greatest punishments on themselves. Death for Lelouch who wishes for a tomorrow with his sister, life for Suzaku who wishes to atone for his sins through death."

Picture of that page in the guide book

Many many many more can be found in the Code Geass community database.