If AI was putting people out of work at that rate the remaining businesses would be hugely profitable so there would be a huge tax base. The economic output would be the same or higher.
If you are suggesting people would choose not to work if we had UBI, the evidence from trials so far is that it does not happen.
Corporation tax is much lower and easier to dodge than income tax. Corporation taxes were only 11% of UK government income compared to 28% for personal income tax, 18% for national insurance and 17% for VAT (sales tax). If a company did develop AGI, it would sell services in the Uk and pay licenses to the technology in a subsidiary in a low-tax durisdiction like we have with ireland for the past couple of decades.
If you are suggesting people would choose not to work if we had UBI, the evidence from trials so far is that it does not happen.