Can a 24 core prostate cancer biopsy cause impotence?

Yes: Yes but not always.

See below: Prostate biopsies are done under ultrasound guidance and usually 6-12 cores are obtained (variations exist but 24 cores be unusual - did you mean gauge?). Usual complications are blood in urine or ejaculate for few days, local pain and discomfort. Infection may occur uncommonly. Rarely injury to blood bessel with internal bleeding has been reported. Impotence would be very rare if at all reported.