Welcome to Android Central! I don't see any SM-T377 variant higher than 7.1.1. https://www.sammobile.com/samsung/galaxy-tab-e/firmware/#SM-T377V. If you want Oreo, you'd have to look for a custom ROM based on Oreo, designed for that specific model -- check the forums at XDA-Developers.com, which is a better resource for that sort of thing.