No I personally think that Anastacius is still alive because in an earlier chapter when Aeternitas attacked Alpheus and he used magic to knock back Anastacius I think Aeternitas was able to take over and even said "Thanks to you, it seems that it'll become much easier to move about" Anastacius has probably been holding him back all this time yet getting weaker and weaker.
Yeah cluade killed him but since that evil being entered him they were both alive
Anastacius is barely breathing when Aeternitas found his body
I think Anastacius already dead, on the day Claude stab him, he said he was still conscious right? And i think the black silhouette on chap. 89/90 i think that was Atharintas?( I dunno the spelling), that kid whom Lucas said his magic was weak, I think he possessed Anastacius body, because in chap. 89 he said that he needs to leave before Lucas arrived right? Cause he didn't want Lukas to know that it was HIM, and by HIM, i think he was pertaining that hes Atharintas. And remember that Atharintas was known as the strongest emperor right? I think if even Atharintas is dead he could still be alive by possessing someones body, and he chose Anastacius body. Long story short, Atharintas possessed Anastacius body, but if he knows that Janette's Anastacius daughter is because Astacius memories still remains?