{W}, {T}: Put a +1/+1 counter on target Soldier creature.
Each creature you control with a +1/+1 counter on it can block an additional creature each combat.
The second ability is cumulative. That is, each creature you control with any +1/+1 counters on it can block an additional creature for each Cenn’s Tactician you control. Cenn’s Tactician doesn’t care whether the creature has any +1/+1 counters on it beyond the first.