I believe you can do it.(can,可以)
I believe you will succeed.(will,绝对)
以上两个是“〔我〕相信你一定可以成功的”
Believe that you can do it.
Believe that you will succeed.
这两个是“〔你要〕相信你〔自己〕一定可以成功的”
I believe you will definitely achieve success.
I believe you can make it!
You surely will succeed !
I am sure you will make it (to succeed).