Hi lemoncurry - I'm a tech-knowsomething, and KC is right. You can't find our from a GIF file. The best thing you can do is try to find a similar font.
If you know anything about Adobe Illustrator or Photoshop, you can open the GIF, convert the image to RGB, then create a new layer and begin experimenting with fonts.
However, if you are dealing with a file from a professional designer, it is likely that you cannot find the same font for free. (Good fonts cost money.) You will probably have to settle for something similar.
Cheers