Not sure about GIMP, but the technique is called gradient.
Just find out what that font is and recolor it by using gradient from dark blue to white.
Then add some border to the text and that is it.
Obliviously not the same font and not the same colors, this is just an example of gradient font.
Sorry I cant do more, but I am not familiar with gimp. I could help you with PdN if you want to.