I know City isn't stable but it is only in a couple of matches. With their formidable Squad and brilliant coach, No one would doubt that they would bounce back to their unbeaten form.
Speaking of Liverpool's scoring ways, I will only consider their number of goals too small if they can't score against a weak team but their last match was against a strong side who also needed a win. Liverpool will be better again.

Liverpool's present performance is by no means encouraging. It will not be a successful win if Liverpool plays against Brighton with the intention of winning back revenge. Brighton is performing at their peak level right now. What I anticipate is either a draw or a victory for Brighton in the last minutes of the match.

Better luck next time, I think it's going to be easier to get good predictions in next rounds but some clubs are playing both Championship and FA Cup, so I expect a lot of rotations to rest some players.
I will ride on top of Burnley and Sheffield Utd good form as long as I can, but they can't continue with good results in the rest of the season.
Sheffield Utd is amazing at half time, so I am always picking them to win both half time and full time.

I kinda disagree, at a top level as a player you cannot take your position in the team for granted. If you lose it, improve and try to get it back.

Both Henderson and Fabinho have been in terrible form this season, that's why we're even discussing Bajcetic & co. Otherwise we'd be starting with our top players for sure.

Both also compete fiercely on the premier league which means they will play to show who is the best in England. Both also have motivated to pair premier league and FA Cup trophies for this year. So when we look Man City after a comeback from behind 0-2 in 1st half vs Spurs today, Man City seem still have mental champion which Arsenal Haven't has, so it's hard for Arsenal because have lost several times on Etihad Stadium also.

Chelsea are like haunted by Manchester City all the time. 

They were eliminated by Manchester City in the 1/32-finals already. The final score was really heavy also like 4-0. Let's see if Arsenal will be able to eliminate the Manchester club in this round. This will be the first time these clubs facing each other in this season also. I don't have any doubt both sides will care about this game as much as the Premier League ones. It is in Etihad so this can be seen as a significant advantage for Manchester City. I remember Arsenal struggling against Manchester United away. I think a similar scenario could happen here also. I think Manchester City can eliminate them.

Yeah both teams have the bargain right of winning it. On current form Arsenal should win it. But I am going for a city win because of some conditions.
1. Both teams will like to rotate their players with city having a superior second team.
2. Arteta wouldn’t take this competition too serious since he has won it before while Pep might see the cup as the only winnable domestic trophy with Arsenal on the verge of clinching the EPL title and them being already knocked out of the carabao cup already. In all I think either a win or lose, both will benefit Arsenal. A win will make them one of the favorites to win two domestic title and possibly do a treble should they triumph in the Europa too. A lose could see them having to play lesser competition and could help conserve more energy or prevent fixtures piling up as the season goes on

I think the match is going to be a strong match and the winner will be determined by the team that will utilize the opportunity they have to score just like what happened between Arsenal and Manchester United in their game in the EPL last weekend. Arsenal and City are first and second in the league table and yes I agree with you they can settle in a draw in the game and go on to battle in the league and City will be hoping to win to reduce the chances of Arsenal winning the league and Arsenal will push to win to extend their gap with City and keep their title hope alive so I think we need to focus more on the performance of the two teams instead of focusing on City as if they are playing better then Arsenal.

 This fixture isn't going to determine if the winner will top the league table but is like a test for both teams getting ready to face each other whenever they'll meet in the first time in the EPL fixture. Both teams haven't played against each other since the beginning of the season, and with Arsenal's successful run I think they can match Man City in this FA CUP game but both teams will be very careful not to make mistakes. The first half of this great encounter might end up being goalless if possible a 1nil lead, to whom I can't tell.
 Arteta is really doing a great job and if he gets past CITY then he's definitely going to win the FA CUP.