Buddhist tradition describes Maitreya—Metteyya in Pāli—as a future Buddha who will appear in a distant age after the teachings of Gautama Buddha have disappeared. Early texts do not give a modern calendar date for his appearance.

Maitreya in early Buddhist tradition
The Cakkavatti-Sīhanāda Sutta in the Pāli Dīgha Nikāya speaks of a future Buddha named Metteyya arising when human conditions have changed dramatically and lifespan has again become extremely long.
The text presents a moral and cosmological sequence rather than a date that can be converted into a modern year.
Maitreya in Mahāyāna Buddhism
Mahāyāna traditions developed extensive devotion to Maitreya. He is commonly described as a bodhisattva dwelling in Tuṣita heaven before his future birth as a Buddha.
Practitioners may aspire to meet Maitreya, be reborn in Tuṣita, or receive his teaching in a future age.
Can anyone predict the date?
Historical movements have sometimes announced dates or identified living figures as Maitreya. Such claims are not a universal Buddhist teaching and should be distinguished from canonical traditions.
Because scriptures do not supply a usable Gregorian date, precise modern predictions depend on later interpretation.
What the teaching symbolizes
Maitreya represents the continuity of awakening: Buddhism teaches that Gautama is not the only possible Buddha. The future Buddha also symbolizes hope that the Dharma can arise again after periods of decline.
Devotion to Maitreya has inspired art, monasteries, statues, pilgrimage, and meditation across Asia.
Short answer
Buddhist texts say Maitreya will appear in a distant future age, but they do not provide a reliable modern calendar date. Claims about a specific year are later interpretations.