Can cocacola cause oligospermia?

Sperm likes Cola :) There is no evidence that colas decrease sperm counts. Men should be careful of smoking, alcohol, heat (sauna, hot tub, hot baths), laptops on the lap, excess cycling and other extreme sports, medications, and recreational drugs. Undescended testicles and varicoceles are causes of poor sperm counts and function.
Unlikely. Moderate caffeine intake unlikely to affect spermatogenesis. If oligospermia is present, consider a urological evaluation (may involve more detailed history, a physical exam, hormonal profile, scrotal ultrasound, etc.) with a urologist to determine its etiology.