The ability of Gideon’s Company triggers just once for each life-gaining event, whether it’s 1 life from Ajani’s Welcome or 2 life from Battlefield Promotion.

If Gideon’s Company is dealt lethal damage at the same time that you gain life, it won’t receive counters from its ability in time to save it.

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, Gideon’s Company’s ability will trigger twice. 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.

If you gain an amount of life “for each” of something, that life is gained as one event and the ability of Gideon’s Company triggers only once.

Putting a loyalty counter on a Gideon planeswalker doesn’t cause any of its activated abilities to become activated.

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.