538's Republican primary polling tracker is live now. Trump has a 23 point lead on DeSantis. He's gained 4 points on DeSantis since the indictment. While it is still early the first contest is less than 10 months away. And historically polling at this point in time is actually somewhat predictive. A candidate like Trump polling at 49% is strongly favored to win the Republican nomination.
This is especially the case given how Republican primaries are set up with so many winner take all contests. The percentage of winner take all delegates actually further increased in 2020 from 2016 to a whopping 30% of delegates allocated by winner take all. So the leading candidate has an even stronger advantage.
Of course the actual primary will be decided in each state contest, so state polling is more valuable. But even there Trump is generally leading DeSantis.
Unfortunately DeSantis is well-known among Republicans, so unless something significant happens I'm not sure what will change his polling. And the indictment seems to have only helped Trump among Republicans