He delayed the case enough (almost 13 years) so that he's now more than 70 though and I doubt he stays to long in prison because of his age.
But it's nice to see that he couldn't run away from justice forever and is finally in jail.
His case is going to appeal but the court decided to still jail him now "provisionally" (exécution provisoire), which sounds like a political play. Coincidentally, the same is happening to Le Pen with respect to the decision to ban her from elections...
As for "delaying" the case, this is just the French court system for you. Everything takes years and years.
He should definitely be in jail, as some of the things he's been charged with, and also in other cases sentenced for, were conspiracies to rig his trials and attempts to lean on witnesses, in cases including, but not limited to, this very trial [1]. Him being behind bars is necessary to stop his attempts to rig his own trial.