Under Wild Magic Surge it states:
Immediately after you cast a sorcerer spell of first level or higher, the DM can have you roll a d20.
Since Magic Initiate has you choose spells from a specific class, would a Wild Magic Sorcerer theoretically be able to Wild Magic Surge when casting those spells, assuming they chose from the sorcerer list?
Best Answer
Yes
The key part of the Wild Magic Surge language is cast a sorcerer spell.
If you had used Magic Initiate to gain spells from another class, those would not be considered sorcerer spells (supported by the language in magic initiate below from PHB, 168)
But a Sorcerer spell is a sorcerer spell, and if you picked your Magic Initiate spells from Sorcerer, then they'd be potentials for Wild Magic surges.
Everything is kept within the sorcerer class and spell list, it all fits under the sorcerer umbrella.