Stone Cold Steve Austin was part of the big announcement for the WWE Network at the CES show, but is not booked to be a part of Wrestlemania 30, at least not yet.
While anything is possible, all signs point to Austin not being in a match at Wrestlemania XXX.
Recently on his podcast, Austin noted that he would like to be at WrestleMania, and mingle with the talent, but nothing is signed or booked. Because of the timing and lack of buildup, the idea that Austin will actual wrestle is considered all but dead.