According to Greek broadcaster ERT's official announcement, Stefania will represent Greece in Eurovision 2021.
Stephania who is decided to participant Eurovision 2020 will represent Greece in Eurovision 2021.
You can find ERT's official announcement here
In particular, the official announcement of ERT states:
A decision by the European Public Radio and Television Union (EBU) has canceled the Eurovision Song Contest in Rotterdam due to the coronavirus pandemic.In his letter to EBU members, competition executive Jon Ola Sand said -: "Our dear partners and friends, We are at a disadvantage in announcing the cancellation of this year's Eurovision in Rotterdam. In the last few weeks we have worked out a number of alternative projects aimed at holding this year's competition, but the uncertainty caused by the spread of COVID-19 in Europe in conjunction with the security measures imposed by both the Dutch authorities and governments of the participating countries led the EBU to the difficult decision not to proceed with Eurovision 2020 as planned. The EBU, NPO, NOS, AVROTROS and the Rotterdam authorities are continuing discussions on the competition in 2021.
ERT has already assessed as very positive the way in which the Greek and European audiences accepted this year's selection of the talented Stephania Luberakakis , as well as the cooperation she had with her. ERT intends to continue this cooperation over time , as the EBU's final decisions become known.