Anything that adjusts your life total upwards is considered life gain.
If you're at 20 life, and you play Providence, it causes you to gain 6 life. If an effect prevents life gain, you will stay at 20.
This is clarified right on Providence's Gatherer rulings:
7/13/2016 For a player’s life total to become 26, the player gains or loses the appropriate amount of life. For example, if your life total is 4 when Providence resolves, it will cause you to gain 22 life; alternatively, if your life total is 40 when it resolves, it will cause you to lose 14 life. Other cards that interact with life gain or life loss will interact with this effect accordingly.
September 8, 2017 2:50 p.m.
Ah ok thanks. As I said I wasn't sure about cards that just are your life total is now this deal with it