Daredevil exists in the world of Spider-Man's upcoming PlayStation 4 game. Sony's Spider-Man was the showstopper at their E3 2018 press conference and it is one of the PlayStation's biggest games for 2018. While the game will adapt a large swath of Spider-Man mythology, it's unclear how (if in any way) the release will interact with the larger Marvel universe.
Spider-Man will have appearances from nearly every Spidey character imaginable. Miles Morales is in the game, Mary-Jane Watson is a playable character and a whole host villains will be out for Spidey's blood - including the villain of Netflix's Daredevil, Wilson Fisk aka. Kingpin. Evidently, Matt Murdock will be another citizen of the virtual New York and could very well interact with Spider-Man as Daredevil.
The proof of Matt Murdock's existence was uncovered by @JamesConoway on Twitter. By giving a closer look to some of the promotional material for the game, a "legal ad" for Nelson & Murdock was spotted. This is, of course, the name of the law firm that Matt Murdock runs with his best friend, and legal partner, Foggy Nelson.
All this Easter egg truly confirms is that Matt Murdock is a part of the world of PS4's Spider-Man. It doesn't necessarily mean Matt is Daredevil and it certainly doesn't mean that he'll appear as a character in the game. However, the reference does make it more likely that Daredevil could be a NPC in Spider-Man or even get his own spinoff or DLC set in the same world. Marvel has stated before that their video games are not tied to or based upon their movies. While Daredevil and Spider-Man haven't interacted in the MCU, they could in the realm of video games.
Of course all of this is some very heavy speculation. The Easter egg could be nothing more than an Easter egg. One of the inspirations for Spider-Man is the Batman: Arkham series, which was developed by Rocksteady. In the Arkham franchise, there are a ton of Easter eggs and references that never led to a character appearing in the game. Lex Luthor's LexCorp had billboards. Green Arrow's Queen Industries logo was plastered all around Arkham Knight. Neither Lex nor Green Arrow showed up.
However, Batman has always been a rather isolated character, much more so than Spider-Man, who exists in New York City and along with a number of other Marvel characters. In the comics, Spider-Man is almost always interacting with another hero that is based in NYC, including Daredevil. It would feel very natural for the video game to have Spider-Man exist in that larger Marvel world.
In addition, Square Enix is planning a mysterious Avengers game. While that title will be multi-platform, not PlayStation exclusive, it would be an interesting (if risky) idea for Marvel to connect the untitled Avengers game to Spider-Man. The two games could create a Marvel Gaming Universe. If Daredevil was included in Spider-Man that would be a big step toward making that dream become a reality. However, that is a very big "if."
On the other hand, it might be in Marvel, Sony and Spider-Man developer Insomniac Games' best interest to just focus on the world of Peter Parker. Daredevil can exist but he doesn't need to be involved. For now, fans can still dream about the wonderful virtual Marvel world that could (maybe) exist.