If the entering creature’s power changes to 3 or less after it has entered the battlefield, you’ll still draw a card.

The entering creature must have power 4 or greater as it enters the battlefield, or Kiora’s first ability won’t trigger. Static abilities that raise or lower a creature’s power are taken into account, as well as any +1/+1 counters the creature enters with. However, you can’t have a creature with power 3 or less enter the battlefield, raise its power with a spell, an activated ability, or a triggered ability, and have Kiora’s ability trigger.