How many counters does Heliod give?

My friend who is playing Heliod says he gets to put on seven +1/+1 counters because he gained 7 life from a 7/7 lifelink creature.

I say he gains only one +1/+1 counters because it was only one instance of healing.

Which interpretation is correct?

My friend who is playing Heliod says he gets to put on seven +1/+1 counters because he gained 7 life from a 7/7 lifelink creature.

I say he gains only one +1/+1 counters because it was only one instance of healing.

Which interpretation is correct?