To find how much Gabriel's pumpkin weighs, we need to add the weight of Marcos' pumpkin (1.37 pounds) to the additional weight (0.24 pounds) that Gabriel's pumpkin has over Marcos' pumpkin.
So, we calculate:
\[ 1.37 + 0.24 = 1.61 \]
Therefore, Gabriel's pumpkin weighs 1.61 pounds.