That's not true; GPUs basically always use the latest process technology available, just like CPUs. Recently, there have been some degenerate cases where a new process is (at least initially) slower and more expensive than the previous one; but in general, they always move to the latest and greatest process, once that process is capable of making a better product.
As for die size, the big GPUs are way bigger than CPUs. A 22-core Xeon Broadwell E5 from 2016 is 7.2 billion transistors, and 456 mm^2. The NVIDIA GP100 chip (also 2016) is 15 billion transistors, and 600 mm^2. The AMD Ryzen (2017) info I can find says it's (probably up to) 4.8 billion transistors.
I have no idea what you mean by "tolerances". Maybe you mean "process variation", which is a natural part of any semiconductor manufacturing - and is controlled by the fab (TSMC, GlobalFoundries, Samsung, Intel), not the chip designers (Apple, NVIDIA, AMD, ummm Intel again). The design houses ship off the chip they want - and the fab produces it, with some chips a little hotter/faster than others. Over time, they can tighten up the process so it has less variation and higher yields, but nobody is "running wild" with anything.
It's complicated too, because the node names are really just marketing hype. Just as "Kaby Lake" is a name that Intel gave to a collection of optimizations put in a single chip, or "Pascal" is a name that NVIDIA gave, or "Ryzen" is a name that AMD gave – 14 nm is a name that some fab gives to their latest collection of optimizations. There's no one measurement that corresponds with the marketing name any more, like there was until the early 2000s. [citation] The upshot of this is that Intel's 14 nm isn't the same as TSMC's 14 nm or GloFo's 14 nm, so you can't necessarily compare them. Intel does generally have an advantage in this space, however. That said, everybody pretty much uses the latest, greatest process technology available to them from the fab they have chosen. And it is often the case that a GPU is one of the first things manufactured in a new process at a fab, so they aren't benefitting from anybody prior - especially not at a different fab, because the fabs don't share their secrets, or even the same set of features (as noted previously).
Also, with a brand new process, yields can be very low, so a given company may choose to reduce their risk by making their first chip on a new process either a die shrink of a previous chip, a minor revision to an existing architecture (Intel's "tick"), or a small low-performance chip. Once the kinks have been ironed out on one of those "easy" options, they can shift the bigger, higher-performance chips to the new process. But in some cases, if they started out on the big chips, the yield would be 0% - or if not 0%, the cost of an individual chip would be so high that no consumer would ever pay for it.
And while I will grant you that GPUs have *less* cache, they do still have some caches and other memories. A GP100, for example, has 14 MB of register files, 4 MB of L2 cache, 3.5 MB of shared memory, and 1.3 MB of L1 cache. That's still well shy of the 22-core Xeon I mentioned earlier, which can have up to 55 MB of LLC, but it's a pretty good amount all the same.
The real reason that GPUs have always outpaced CPUs is because they are inherently parallel. In addition to all the architectural optimizations that are made every year, they also add more cores every year; while most of us are still using something in the vicinity of quad-core CPUs, just like we were 5 years ago. Also, the parallelism of GPUs means that they have more freedom for architectural changes to yield throughput enhancements. A CPU is largely targeted at single-thread performance, so most of the optimizations they make will enhance that. A GPU architect can make similar optimizations to enhance a single thread's performance, but they can also make changes that only help parallel computation.
So GPUs are arguably more advanced than CPUs, or at the very least on par with them - and they will continue to outpace CPU development for the foreseeable future as well.