This is probably a better question for immigration attorneys. That being said, I think a felony is an automatic denial of Deferred Action. He needs a criminal defense attorney to have his case reduced to a misdemeanor to qualify.
Seth Weinstein, Esq.
Practicing throughout Southern California
This reply should NOT be considered a legal opinion of your case / inquiry. At this time I do not have sufficient factual/legal documentation to give a complete answer to your question and there may be more to the issues you raised then I have set out in my brief reply.
Your best bet is to hire a good criminal defense attorney and fight both charges. Your son will be ineligible for DACA if he is convicted of a serious crime possibly inclusive of DUI. Therefore, you may need to address the criminal case first.
Of course he will not be automatically deported.He will be issued a Notice of Hearing, can appear before an immigration Judge and seek any available affirmative relief. If he is free of criminal convictions, he stands a better chance in all of the above scenarios. Good Luck.
The jail issue for the criminal matter is different than removal. If convicted of a DUI, it is usually a bar to obtaining DACA. That said, there may be other avenues to keep him here in the U.S. and fight the deportation. Please retain immigration counsel immediately.