[gambiting]

People have performed all sorts of surgeries for thousands of years, and while yes, the percentage of them getting infected and resulting in death was probably very high, it doesn't mean that every single surgery ended that way - in the end, people have been amputating limbs or getting wounded on the battlefield and surviving without any sterilization. So while it's rather unlikely, it's possible that Caesar's mother survived the operation.

[ptaipale]

True, but deep wounds in the abdomen are much, much more difficult regarding infections than e.g. limb amputation. Surviving that was very extremely unlikely. Roman law said that the child must be cut out of a dead mother's womb, to bury it separately, but by that time the woman was dead or dying.

As far as I could find, the earliest written source claiming Caesar was born with C-section is from about 1000 years later.