Hi momoftwo. I'm so sorry to read about your dad's situation. I'm no doctor and I don't think anyone on this board will be able to tell you how long you will have with your dad. Hopefully, you will have many, many years.
The only suggestion that I have for you is to make sure that your dad is being treated by a hospital and team of doctors who have a lot of experience with bladder cancer. If he is already being treated by such a team, then talk to his doctors to find out what they feel is his best treatment path. If he isn't at an experienced facility, then perhaps you can help him seek a second opinion from another, more-experienced facility.
There's always hope, so don't give up too quickly. Please keep us posted on how your dad is doing.
Best wishes to you and your dad.