If information from China is to be believed, US sanctions affect only Huawei's upcoming order with the TSMC. It will not affect orders that Huawei already placed, and the Kirin 1020 SoC is amongst them.
The Kirin 1020 arrival won't be affected by US sanctions, it seems
That also means that the company's 5nm and 7nm processors, in general, will come from TSMC. That also means that the Kirin 1020 will be in time to fuel the Huawei Mate 40 series.
It will also fuel the Huawei P50 series next year, almost certainly. The Kirin 1020 will be a direct successor to the Kirin 990, which is amongst the best mobile processors in the market at the moment.
The Kirin 1020 is expected to arrive later this year. Its predecessor, Kirin 990, was officially revealed in September last year. So, the same will probably happen with the Kirin 1020.
That chip will become official around the time IFA In Berlin comes around. IFA in Berlin will take place this year, it seems, but it will be open to journalists only, at least according to the latest information.
The US managed to make life even more difficult for Huawei recently. The US Commerce Department basically requires manufacturing companies that use equipment from the US to get a special incense to supply to Huawei, and some other companies.
TSMC is using equipment from the US, needless to say, so that creates quite an issue for Huawei. As if the lack of Google services was not enough, the company's main hardware component is not in jeopardy as well.
SMIC already manufactured one processor for Huawei
SMIC already manufactured one processor for Huawei, though not a flagship one. Reports have been saying that Huawei will turn to SMIC for help, but the question remains if the company is capable of replacing TSMC.
The answer to that question is probably no. Rumors are saying that SMIC does not have the technology to produce Huawei's high-end processors. The the same goes for capacity, actually, but nothing has been confirmed just yet.
China invested a lot of money into SMIC quite recently, though. The company could flourish really fast thanks to such financial gain, so we'll see what will happen.
Do note that the Kirin 1020 SoC does seem to be on schedule, as US sanctions won't affect it, it seems. That information has not been confirmed, though, so take it with a grain of salt.