There are 18 seniors on the roster:
Roster 2007-2008 - UT Sports Official Site
then add the number of transfers, players who get kicked off, or leave early for the draft, etc. I'm assuming Fulmer went into the season with a full roster.
I only remember Coker getting kicked off so that goes up to 19. They will mostly sign more since some usually don't qualify.
David Holbert and Antonio Gaines will be back next year.
However, don't your scholarships only last 5 years, if so than Gaines shouldn't have one. I believe he has been here five years already.