If the rooster that died had a respiratory virus, chances are Bruce has it, also. If you had gotten a necropsy when the other rooster died, it could have told you what killed him and you would then know how best to treat Bruce.
There are two possibilities - a bacterial infection secondary to the virus, or a fungal infection. The first one you would treat with Tylan, while the second you would treat with Oxine in a vaporizer. You may need to order it off Amazon as I haven't seen it in any stores. It's a disinfectant that kills fungus.
I would get some Tylan at your feed store and start him on that. If he responds and gets better, you know it's bacterial. If he doesn't get better on Tylan, then assume it's fungal and treat with the Oxine vaporizer. Place the vaporizer in front of a crate with Bruce inside. Drape a sheet or bact towel over the crate so the vapor with the Oxine accumulates inside. Do it for at least 24 straight hours.
If Bruce responds to neither treatment and gets worse, instead, it likely had cardio-pulmonary issues and tumors could be the cause. They are also caused by a virus. If Bruce ends up dying in spite of your efforts to treat him, I urge you to get a necropsy. A vet could tell you where to have it done or ask at your nearest university agricultural extension office.