Bayern Munich always been a tough team in Champions League, unfortunately they're in tough bracket since they will meet either Real Madrid or Manchester City in order to enter final round.
It is during the QF draw that teams would know the opposition teams that they would possibly meet on their way to the final, mind you that after the RO16 fixtures are over and we now have 8 teams, there would be another draw, that is when you can know the teams that would face who in the next rounds, but for now that's not possible and you can't know if Bayern Munich would face either Real Madrid or City in the next rounds.
This system is definitely more interesting, because the teams that qualify for the quarterfinals will be drawn again and thus, no one really knows which team they will face next. But ya,regarding Bayern Munich in this round of 16 I think it is clear, that Bayern Munich will probably easily win too. Because ya, considering the opponent to be faced in this round of 16 is Lazio and ya, at least Lazio in this season also does not really have good results in Serie A, Because Lazio very different from last season.
Anyway, Bayern Munich clearly has better quality than Lazio because ya, Bayern Munich is always in and plays in the Champion League every season. Therefore, Bayern Munich certainly has better quality and mentality than Lazio and thus, it might be easy for Bayern Munich to beat Lazio later.