Was his wife Catholic? Did he have a deathbed conversion?
As to any deathbed conversion, Magic 8-Ball says: Not very likely.
First, he was a deacon in the Presbyterian church.
Second, his first wife, Elinor, was the daughter of a Presbyterian theologian. (She died in 1854 during childbirth)
Third, his second wife, Mary Anna, was the daughter of a Presbyterian minister.
Fourth, Jackson was known to have preferred Presbyterians for duty within his officer corps.
See any pattern here?
Also, a doctor and aids were next to him during his final days/hours, and there is no report of any deathbed conversion, so suffice it to say, he most likely died believing in the protestant Presbyterian faith.