No, at least according to the information presented in the source they reference, which just doesn't actually attempt to establish any correlation.
Ministry experts determined that he was likely to have contracted leukemia following cleanup work at Fukushima Daiichi. They found he had been exposed to a total of 19.8 millisieverts of radiation from his work at various plants. He was exposed to 15.7 millisieverts at the Fukushima plant.
Compensation is granted if a nuclear power plant worker has been exposed to annual radiation of 5 milliseverts and has developed cancer more than a year afterward.
Note that, (0), he was diagnosed with leukemia, and, (1), compensation is granted based on the facts of, (a), receiving certain level of radiation, and, (b), developing a cancer certain time afterwards.
Note that leukemia in Japan is often caused by HTLV-1, which is endemic in southern Japan, and is known to cause leukemia.
It would appear that HTLV-1 status of the worker may not play any role in whether or not compensation is granted.
As such, there is simply not enough hard evidence to conclude that it is radiation, and not HTLV-1, that the condition has been directly caused by.