He has been charged with evading arrest with a vehicle. This usually means he took flight in a vehicle when the police tried to pull him over. This is a serious charge as it can lead to a high speed chase in which people can get injured. He needs an attorney.
I can't tell you how much time he'll actually do (or if he'll even do any at all), but I can tell you that offense is now a third degree felony, which means that the punishment range is 2-10 years in TDCJ. He may be eligible for probation, it might be able to be reduced to a misdemeanor, or it might be such a bad case it gets dismissed altogether, so I certainly wouldn't say it's a certainty that he's going to prison for somewhere in that range (also, if he has felony priors, that could also increase the punishment range). Felony evadings are sometimes filed in cases where they're clearly not warranted, and a review of the patrol unit video can make it pretty obvious that it's not a good case, so don't give up hope just yet. He does need a good attorney to pursue that angle and others, though, so that should be the first step. Good luck.