The amount of ejaculate matters if there is very little coming out and/or there is much less than you once had. To some extent, the amount of pleasure from an ejaculation is determined by the volume released. Other than keeping in good health through diet, avoidance of tobacco, proper liquid intake, exercise, and sleep, I could not tell you how to increase your ejaculate, but perhaps others can.
Less frequent sex/masturbation will probably increase volume, up to a limit, and depending on what your current frequency is.
Like Bionicle, I'm not sure why this would really matter?
You can't. Withhold yourself may increase your pleasure but not volume. The testes nly prodice "x" amount and the rest will be considered waste and absorbed by the body. Why would you wish to increase the volume anyhow ? Seems to me that you may feel volume= more intense climaxes ? Not so friend !
P (age 50)