Both PSG and Manchester City are in an uncomfortable situation in the Champions League. If PSG is very eager to win the Champions League once and then the trophy will be stored in the cabinet, then it is very unlikely that PSG will give up amidst Manchester City's unstable conditions this season. This match will be used well by PSG because PSG will act as the home team and for both of them will play the game in their best form so that it will not be remembered by many fans if they become a team that fails when the new Champions League format is implemented.
Yes both PSG and Manchester City are feeling a lot of pressure in Champions League. PSG really wants to win title and put trophy on their shelf. So they probably can not give up especially since Manchester City has been playing inconsistently this season. PSG will try to take advantage of this chance especially since they are playing at home. Both teams will try their best to avoid being remembered as team that failed in first year of new Champions League format. This game is very important and it should be very exciting and competitive match between two of best teams in Europe.
Both teams will feel the pressure to win which could be extra pressure for Manchester City as they were on the back foot towards the end of the year due to being behind in the points table which looks positive at the beginning of this year. Their confidence has been boosted by their impressive win at Ipswich Town in the last match and they are looking forward to showing a good performance in the next match. You are right that PSG are not ready to give up and they are trying their best. Kevin De Bruyne-Phil Foden's good performance in the match has played a special role in changing the fortunes of the team. Yes, fans are waiting for another exciting match and it is expected that the last four time club champions Manchester City will overcome their failure with their consistent good football. They have moved up to fifth in the points table with full three points in the last match which will further motivate their team but they are still 12 points behind the leaders Liverpool and Guardiola's team will have to work harder to move up.