So more like 3–4 years and not 5, but still behind
I am not sure if it is that simple. Their process is using DUV and I assume a ASML lithograpy machine they got from somewhere. The next big step and what the current leading edge uses is EUV, so a different technique.
Unless they get their hands on one of those machines, which I assume will be prevented at all costs through sanctions, they’d have to reengineer that themselves. Something they havent done even for this 7nm lithograpy machine. EUV was decades in the making with an insane amount of research spending. Even with maybe not having to start from scratch this will be a tough nut to crack.
Unless they solve this problem they might push DUV a bit further, but then hit a brick wall. So I am not sure is your estimate how far they are behind is accurate in this sense.
That said, as someone else posted. 7nm is already plenty good for a lot of stuff.