GPU Gems may be old-ish but many the techniques being used are only now being incorporated into realtime graphics. Main reason is because they are (were) cutting edge research papers created using absolute top of the line Nvidia based graphics cards. A few years later and those cards are starting to become more mainstream.
As far as a book goes you will likely not find one with even newer techniques, these are research papers, each one of the chapters in GPU Gems (1, 2 & 3) has enough information crammed together that could fill an entire book. You will have to look into each topic instead of looking for a single book containing them all.
Which areas are you the most interested in? It would be easier to recommend a book based on your answer.
I mentioned before as well, but is a very complex and far reaching topic (creating your own rendering solution). GPU Gems outline small pieces that can be added to a rendering setup (such as UE4), but are not a complete rendering solution, just the “Added Features” you can add to the core renderer.