You should use Irish moss or Whirlfloc during the boil. I use 1/4tsp of Irish moss in 5 gallons (1/2tsp in 10 gallon), so 3tsp (1tbsp) of irish moss should be the proper amount. Or use 6 whirlfloc tabs.
Those are kettle finings. They only work when added during the boil. They both aid in coagulating and precipitating proteins in the wort. Gelatin won't help if you don't add these.
Gelatin is a cold-side fining. Like Biofine or isinglass. You add these post fermentation. I use 1tsp of gelatin in 5 gallon. that's 4TBSP in 60 gallons. These will drop out yeast, and other cold side haze. They won't drop out chill haze that's formed from protein complexes (i.e. the haze that irish moss prevents).
Long story: Buy some whirlfloc or irish moss. It really helps make beer clearer.