This is a common and important question. The answer: yes, the BaZi chart is based on the actual birth moment, regardless of delivery method.
In Chinese metaphysics, the moment of the first breath — when the baby's energy field becomes independent from the mother's — is what matters. Whether that moment occurred via natural labor or surgical delivery, the energetic imprint is the same.
Some argue that "chosen" birth times don't count. But even scheduled C-sections have unpredictable elements — the actual delivery time may differ from the scheduled time, and the baby's own karma and energy participate in the timing.
From a practical perspective, millions of C-section births have been analyzed with BaZi, and the charts are as accurate as any other. The universe imprints at the moment of arrival, not the method of arrival.