Are all Orange Cats Male?

No, but male orange cats outnumber female orange cats by about three to one.
The reason for this has to do with chromosomes and genes, put very simply the same pair of chromosomes that determine whether a cat is male or female also determine the color of the fur.

Why are there so many orange (ginger) and white cats? (a glance at the orange cat pictures to the right will confirm this). This is because white is not actually a color, but is in fact the absence of any color, and the gene that is responsible for the repression of color is more powerful than the genes for any of the colors, including orange.  This has to do with genetics - the orange color is a dominant gene carried on the X chromosome.

Males have an X and a Y chromosome and the Y is negligent when it comes to color, so if a male's X chromosome carries the dominant orange color it will be an orange tabby cat.

Females get two X chromosomes but what's interesting here is that if a female gets an X chromosome with the dominant orange color and her other X chromosome is for a different color (which most times it is), those two colors will blend and this is usually when you get a calico or tri-colored cat.

This is also the answer to why all calico cats are females (although I think there are a very teeny tiny number of male calicos just because nature isn't perfect).  I know it can be kind of confusing!!