No, it doesn't stop it. Teferi says:
Each opponent can cast spells only any time they could cast a sorcery.
But copying a spell is different from casting it:
706.10. To copy a spell, activated ability, or triggered ability means to put a copy of it onto the stack; a copy of a spell isn’t cast and a copy of an activated ability isn’t activated.
Therefore, Teferi doesn't affect the Epic ability.