Husbands testicles are left 5 cc and right 6 cc in volume. he does not ejactulate much is the size of testicles the cause?

No, ...: The testicular size (volume) is not correlated with the volume of ejaculated semen, instead, with the size (volume) of seminal vesicles where the semen is stored ready for ejaculation upon reaching orgasm. Largely, average volume of semen is about 1.5-4.5 cc with a wide variation among men reflecting the inborn size of seminal vesicles.

Testicle: The decrease in ejaculate can be due to several factors such as decreased testosterone level. He needs to have a urologist check his testosterone levels . Medications often can cause ejaculation issues especially the ones used for BPH such as flomax (tamsulosin)