Gwanchoksa Buddhist temple - Statue of Buddha Maitreya (Mireuk in Korean)
One should speak of the Bodhisattva Maitreya rather than Buddha Maitreya as he will be Buddha only in the future (in a very long time, several million years or kalpas -largest time unit in Buddhism-...).
The statue, with its particular shape and hat is typical of the style of the Goryeo dynasty, who reigned from 935 to 1392.