Author royalties depend entirely on the author's contract with the publisher. If the contract says they get royalties, they get royalties. If the contract says they don't get royalties, they don't.
The issue of copyright, which other answers mention, is beside the point. The author licenses or sells the copyright to the publisher for an agree sum or share of income. It is that contract, and only that contract, that determines if they get royalties and, if so, how much and when.
In some cases, authors sell copyright to the publisher outright. For one technical book I contributed to, I was paid a fixed sum on acceptance (and did not get my name on the cover). I have no clue how many copies that book sold. I got paid up front.
For another book I contributed too, I got paid nothing at all. My contribution was a single page, and its basic value to me was as an advertising piece. It was touted as an industry glossary written by industry experts, so my reward was reputation by association with the bigger industry names who also contributed. You can buy all the copies of that book you like, but I won't get a cent.
Another book I wrote many years ago now is still technically in print, because it is available digitally (or was last time I checked) but it is totally out of date and hasn't sold a copy that I know of in years. If you bought a copy of that book, though, I probably would not see a cent, because the contract stipulates that royalties are only paid out when the reach a certain threshold (which I no longer remember), so your purchase would probably not make my royalty account reach that threshold.
(Dry the starting tear. I do still get paid from my more recent technical books, thought in those cases I get a percentage of revenues rather than a royalty on sales.)
All that said, it is normal practice that authors of fiction are paid in royalties and that royalties are paid to the author or their estate as long as the book remains in print. So yes, if you buy a copy of their books, it is a virtual certainty that Forsythe and Archer will get a piddly little royalty from the one copy you buy.