One's bladder cancer spreads to the surrounding muscles how likely is it for a patient to survive?

Metastasis. A cancer that spreads is much more likely to be fatal than one that doesn't.
Unlikely. Bladder cancer can be a very aggressive type of cancer. If it has already spread to surrounding structures and organs, it is an aggressive cancer and has metastasized. Once this occurs, the long-term prognosis is very poor.