To my surprise, bookmakers are now pricing Tottenham as clear favourites, with Tottenham's odds at 1.61 and Eintracht's at 2.18. Maybe these are inflated expectations for the first game, which will be held in England?
Playing the first leg at home isn't an advantage.
The odds are 1.61 for Tottenham to qualify for the next round and that would be even lower if they had the second leg at their home stadium.
Teams that have the second leg at home play the extra time at home if the match is tied in aggregate and that's why playing the second leg at home is usually considered as an advantage.