Can my fiance get his visa if he is currently in jail?

Your boyfriend's case presents two separate but equally difficult issues, namely that he is subject of a deportation order for drug offense. There is no opportunity for a fiance visa in this situation. If you marry him however, you can file a Form I-130 petition. But I am afraid, his opportunity to obtain a green card has been severely undercut by the fact of his illegal re-entry. He was never going to get a green card or much of any immigration benefit even if he was able to illegally re-enter as he is automatically subject to s.241(a)(5)INA reinstatement of order of removal. Next, depending on the U.S attorney's office having jurisdiction on his case, your boyfriend likely faces 8 USC s.1326(b)(1) or (2) criminal prosecution. If found guilty, he faces a fairly lengthy jail term, followed by another deportation to Mexico. Regardless of outcome of the criminal prosecution, his deportation that is almost certain to follow makes the odds of any successful legal return to the US very slim. Nonetheless, I strongly suggest that you consult with an experienced immigration lawyer on this case.

The case you describe appears to be quite complex. Retain an immigration attorney to sort things out.

Your question requires an attorney consultation. It is not a simple question that can be answered on this type of forum. There are many factors that would need to be considered and evaluated. His order of removal due to a drug charge and subsequent attempt to illegally re-enter the country complicates his situation. If he is currently in jail, there is a possibility that he may be charged with illegally attempting to re-enter the U.S. after being deported which is a criminal offense. I strongly suggest that you contact an experienced immigration attorney for a face-to-face consultation and give him/her all of the facts surrounding your fiancE's situation. He/she would then be in a better position to analyze his case and advise you of his options.