Oda has cried wolf so many times, so it's understandable that this is another cry. But it would be pathetic tbh.
However, these are some reasons why he might be actually dead:
(1) Kanjuro. He had 2 soldiers with chopped off heads saying Kozuki bloodline is finished. If we take it at face value, that's exactly what happened to the Kurozomi bloodline. And it does look like Kanjuro at least bit the bullet, since Kiku is crying with blood on her sword. Kiku also stated that her wounds will "haunt him in the afterlife" so there was perfect set up for Kanjuro's death.
(2) Once Law retrieves Momo, the war will start, i.e. next chapter. Luffy and Yamato are running towards Kaido. This is the biggest war in One Piece so far, and Orochi's death amidst Kaido/BM proclamation would be the perfect way to start it.
(3) People were saying Orochi was dead and Fukuwhatshisface was shocked as well.
(4) For people wanting Hiyori, Momo, Zoro, Scabbards, etc... to take revenge, understand something. Oda was never for revenge killings, at least not from the protagonist. As much as the fanbase likes this, Straw Hats are not vindictive assholes. Now I'm not saying they never take revenge. They just don't KILL for revenge. Luffy didn't kill Arlong for example. I think the only time SHs ever killed someone was Zoro in Alabasta for some random BW agent, and since then Oda has never made them kill anyone, and certainly not for revenge.
Story wise it would make much more sense for Kaido, his ally in taking down Oden, betraying Orochi, rather than having some cheesy revenge kill story which Oda never goes for.