2020-06-23 : Because Vito's first ability doesn't deal damage, you won't gain life when it resolves if Vito has lifelink.

2020-06-23 : Each creature with lifelink dealing combat damage causes a separate life-gaining event. For example, if two creatures you control with lifelink deal combat damage at the same time, Vito's first ability will trigger twice and you may choose a different opponent for each trigger. However, if a single creature you control with lifelink deals combat damage to multiple creatures, players, and/or planeswalkers at the same time (perhaps because it has trample or was blocked by more than one creature), the ability will trigger only once.

2020-06-23 : If an ability triggers whenever an opponent loses life and causes you to gain life, such as the ability of Exquisite Blood, this will loop until either you win the game or a player takes an action to break the loop.

2020-06-23 : If you gain an amount of life “for each” of something, that life is gained as one event and Vito's first ability triggers only once.

2020-06-23 : In a Two-Headed Giant game, life gained by your teammate won't cause the ability to trigger, even though it caused your team's life total to increase.