V.W.
Hi. I agree with the previous posters. His birthday should be about him, not his status as a brother.
My son is almost exactly 3 years older than his younger sister... like 18 days. So I can relate to a lot of what you are thinking about.
What I would do, is have his baby brother/sister (whichever you have) give him a birthday present. You can shop for it now, and put it away so he doesn't know about it or anything, but wrap it and have the card or tag say it is from "___ (sibling name)". That is all I would do as far as the "brother" side of things. Have the day be about him, not how he relates to his brother.
Just my 2¢