no not likely. your choice of underwear may be important if you are trying to conceive (testicles make more sperm when they are cooler). most of the ejaculate is from the prostate not the testicles and underwear will not effect this organ.
can tight underwear affect ejaculation? . i wear what amounts to tights all the time. i notice especially lately that i can have an erection and all the feelings just fine but can't seem to come to full climax and ejac. does the tight underwear have anything to do with that?