Depending on what system you're on, there are tools that do the conversion job.
If you are on a Linux machine, try replacing your pdf conversion process with the following:
 `inkscape -f input.gif -A output.pdf`
I have no proof that this will work on Mac OSX, and I am certain it will not work on windows. http://zkwarl.blogspot.ch/2006/08/inkscape-tip-use-inkscape-on-command.html