Reasonably enough, aspiring strip cartoonists always want to know what their odds are of being syndicated, and how much money they might make. The answers to these questions are "darn low," and "probably less than a good plumber makes."
But that's not a very satisfying answer, so (at the risk of being a bit silly) let's bring in some more detailed numbers. (All these numbers, btw, are gleaned from Mort Gerberg's 1989 book "Cartooning.") I'll discuss these as if they're accurate numbers because that's more fun, but keep in mind these are just guesstimates (and somewhat out-of-date guesstimates at that).
A syndicate might receive around 6,000 submissions a year, out of which two will be accepted. That's about a 0.033% chance of syndication.
But let's assume that your cartoon is well above average. Sarah Gillespie has said that about 5% of all the strip submissions United Media recieves are good enough to recieve consideration. So, out of 6,000 submissions, around 300 will be worth consideration. Only a couple of those will be picked up, making the odds (for those rare strips in that top 300 catagory) around 1 in 150, or a zero and two-thirds percent chance.
But even if a strip makes it that far, beating the 0.66% odds, it still hasn't made it: some syndicated strips flop, after all. But those aren't odds most of us will ever have to worry about.
What a newspaper pays for a strip varies according to circulation and other factors. On average a syndicated cartoonist will earn $6 per paper carrying the strip, per week. Most comics appear in a hundred papers (give or take), so that's about $600 a week, or $31,200 a year before taxes - an okay salary, but I wouldn't want to raise a large family on it. Some poor-circulation strips make the cartoonist about $100 a week, which is well below the federal poverty line.
In other words, for most cartoonists, strips are not an very lucrative field. If your primary goal is to get rich, this is not the job you want.
That said, let's consider the top end, just for the fun of it: Calvin and Hobbes appeared in roughly 2,400 papers, so that'd be about $14,400 a week, or $720,000 a year. That would presumably be the most a cartoonist could make from newspapers alone, although of course there are additional sources of income available to the most successful cartoonists, such as book collections and licensing.