If he is not convicted I don't believe he can be banned from holding office again.Also, they could ban him from holding future office with only 51 votes.He can be reelected as long as congress does not ban him from holding office after congress convicts him and voters are stupid enough to re-elect him, none of which is likely.This is interesting. I found this on Wiki, so it is what it is (emphasis mine):
A conviction at impeachment trial is not a punishment, and the consequences are limited to removal from office. A party removed by impeachment may then also be permanently disqualified from holding any office of honor, trust or profit under the United States. If convicted and disqualified, the disqualification from public office only restricts the impeached party from serving within positions created under the Appointments Clause of the United States Constitution. Because the right of the States to choose the President is indefeasible, and because the Supreme Court has repeatedly explained that elected officials, such as the President, cannot be “officers of the United States."[39][40];” a party who is impeached, convicted, and disqualified from holding office who is otherwise legally eligible under Article II of the Constitution can still be legally elected as President, Vice President, or any other elected position within the United States.
I've not yet investigated the footnotes in that, but could the possibility exist that, even if convicted, Trump could still theoretically run and be elected?