Spoiler Alert. If you haven't watched the Joker yet, do not scroll down. 

DC and extended cuts of their films are a love story older than time itself. Remember the petitions about the Snyder cut for Justice League?

Snyder cut Justice League
Source: Heroic Hollywood

Well, Joker director Todd Philips hates deleted scenes. 

I hate fucking extended cuts. I hate deleted scenes… They’re deleted for a reason.
Todd Phillips and Joaquin Phoenix
Source: Indie Wire

He tells Collider that he would never release a deleted scene. 

The movie that exists is exactly the movie I want it to be and I will never show a deleted scene

That being said, it doesn't mean that there weren't any good scenes that were left out of the final product. 

Joker
Source: The Wrap

Joaquin Phoenix talks about one such scene that he thought was brilliant but the director wanted to remove the scene to have the movie make more sense. 

There was a scene that, that during the shoot we thought was one of the best scenes and we loved his behavior in the scene, and I’d always really liked the scene. And Todd told me and said, ‘We’re cutting that scene out.’ And at first I thought, like, ‘Wait a minute, what do you mean you cut that scene out?’ And then of course I saw it, and it was very obvious. It has to go.
Joaquin Phoenix
Source: NME

He adds:

And at first I thought, like, ‘Wait a minute, what do you mean you cut that scene out?’ And then of course I saw it, and it was very obvious. It has to go.
Source: Collider

Phoenix also weighs in on the practice of cutting some great scenes to make the film better as a whole. 

That’s just what’s so cool about movies, right? You can have a great scene, it’s something that makes sense, but the movie is the collection of all of these scenes and they have to work together to tell the story, and it actually made that whole sequence so smooth.
Source: Deseret

So the scene we are talking about is between Arthur and Randall, who originally lends Arthur his gun, for the second time in the stairwell. In the final cut of the film, this scene gets a callback when Arthur writes on the sign down the stairwell.

But, according to Phoenix, seeing the original sequence 'makes total sense, and then you’re fine with it'.

Joker
Source: comicbookmovie

That being said, it doesn't mean that Philips and Phoenix do not love the scene. Philips admits that the scene was a heartbreaker and it could have been the last scene he cut out. 

Joker
Source: Inverse

So for now, it's safe to say that we are not getting any more extended footage. But never say never.