Blackgate is the one with Jack right? I don't remember anything about fire pokers from that. I just know that dead friend from Flynn's route said something about fire pokers and that Chase found some in the office building and there were the same number of pokers as cast members. I made that connection a while back tho, so I don't remember how accurate this statement is.
Found what I was looking for. In Flynn and "Sydney"'s talk, "Sydney" takes his fire poker and stabs it into the table, saying "There were six and now there's five.". Shortly before this he says, "A simulation. In here I become 'we' with you". Once Flynn asks if he's refering to him, "Sydney" responds with, "Podpalacz, no.". I looked up what Podpalacz was, and it kept popping up as "arsonist" or "Incediary". Considering the person he's talking about is likely the player, he's likely refering to us as an arsonist. If I'm right in assuming that each fire poker represents a cast member that isn't Chase, or more specifically their routes, then that would add up with the "there were 6, now there's 5". There were once 6 characters, but Sydney died, so now there's only 5, just like the fire pokers. Later in this scene, Flynn asks if everything he's seeing with Syd is real, and they respond with, "It could be. Somewhere in here.", while refering to the firepoker. If the firepoker he has is representative of Syd's route, then Syd would have probably have had to not have died. But yes it could be refering to Blackgate on top, which would make sense considering they're both horror themed.