Question
i got ur message today and i thank you for replying.well i live in austin texas so how long would the tree live? right now its as big as my house.

Answer
Mario,

If the plant is hardy to your area, as it appears to be, it could live for many years.  

If you are concerned about the size I recommend to take it down.  If you want to grow bananas I have included a link to a grower who produces many, many different types that may be more suitable for you.  

http://www.bananaplants.net/bananaplants.html

Gary