Note 5 at Ac 20:10: Some people have argued that because Paul said his life was in him, that this young man was not really dead, just close to it. However, it was after Paul had embraced Eutychus in a similar fashion to how Elijah and Elisha had when raising people from the dead, that Paul said this.

If Paul would have simply discerned that Eutychus was still alive by embracing him, then there would be no explanation for his miraculous recovery. No, there is no reason to doubt that Eutychus was dead, and God raised him up through Paul's faith.