If a Soldier receives a first time UNSAT in the Army National Guard, and receives education benefits, will they be revoking current benefits?

More information is for sure needed on this one. If they missed a portion of BA they should be fine, just have to go awhile for that to "drop off" their record. If they received enough for a separation packet then I would imagine their benefits are revoked. Yet by that time there should have been a counseling for this soldier stating the course of action to be taken, i.e. recovery or separation.
If they are having issues with depression and financial hardship I would direct them to some sources that provide guidance, Military One Source and the like.

UNSAT? As in received a "U" for a day or a portion of a day of drill? I've never heard of anyone losing benefits for getting a "U."

As a prior commander from the national guard, I can positively say that if you are coded with a single U, you will lose your benefits. I took great pleasure in taking a soldiers benefits when they were more than willing to take the money for college but didn't want to attend drill. That being said, if a soldier had a good reason, I would also code them as excused and allow them to make up drill this saving their benefits. It all comes down to communication. Make sure you are communicating with your chain of command to prevent being coded as a U.