Chelsea last two matches very impressive, and perhaps this will make the Blues squad more confident against Newcastle. Apart from that, Chelsea also seems to have found their rhythm, because in 8 matches in all competitions the Chelsea team only one lost. This also proves that their performance already improve, so I'll probably favorite Chelsea in that match, and will bet on them.
Meanwhile, on the other side Eddie Howe may will be not too much pressure squad Newcastle to got winning against Chelsea, and in my opinion maybe they will be play safe because there is an important schedule in the UCL which requires Newcastle players to be fit.
I agree that Chelsea performance looks better in the last 2 matches. Chelsea defeated Tottenham with 4 goals and they could get a draw against Man City. Chelsea showed to us that they are not a weak team anymore, they can challenge the favorite teams in EPL. If they can beat Newcastle in the upcoming match, they must be getting more confident. With the current condition of Chelsea players and Newcastle players, I believe Chelsea players are more ready than Newcastle players. Although there are some injured players in both teams, but Newcastle looks in the worse situation because they almost have no option on the attacking line. All the strikers of Newcastle are injured, I don't know how Newcastle coach can face this problem. If there is no striker who can recover before the match, Newcastle will play without a pure striker. This will lower the chance for Newcastle to win the match, so it makes sense if people assume Chelsea will win the match.
By the way, in Newcastle squad, there are 6 unavailable attackers now. 5 injured players, 1 player gets a suspension for UCL match.