Texas and Georgia already are heavily gerrymandered for Republicans. So is South Carolina.
Texas is a court map IIRC, since Democrats controlled the State house in 2001 and couldn't agree with Perry on a map so it went to the courts. Remember they dropped to 76 seats in 2008--not something that could realistically happen in a Republican-Gerrymandered map. They'll also probably pick up a seat or two in South Texas since they can uncrack the Republican votes there.
Same with Georgia I think, though I'm pretty sure it was a Dem Gerrymander turned Dummymander, so I don't know. Republicans tried to redraw the map in 2005 but got struck down, which is why the current congressional map looks kind of reasonable.
The GOP got to redraw the Georgia state Legislature map back in 2003 after the Dem map was struck down.
Nope, the current state legislature map isn't (mostly) a GOP gerrymander. It was redrawn in 2004 by the GA Supreme Court (majority Democratic appointees, ftr) who found the Democratic plan unconstitutional. When the GOP redrew the Congressional map they only did a "pin point" redistricting of the state legislature maps, altering a handful of districts mostly in the Athens area.