This is just my assumption and I could be wrong but there were reports club's revenues will be around 200m lower than projected due to Covid. Now I think what they meant is of what club's projected budget for 2019/20 would be (1,047 billions) so our revenues last season will actually be around 850m while in 2018/19 they were 990m. So around 140m less than last season.
Barca gets 166m for La Liga TV rights so around 4,2m for every match. With 11 matches not played before June 30th when season/last fiscal year finished that's a loss of 46m. A money the club will eventually get but they can't include this revenues into last season reports. Unless they'll use some really creative accounting.
Club planned to get 220m from Nou Camp revenues - tickets (without season tickets which were expected around 43m) and Barca museum. Now obviously this numbers are fluctuating depending on the opponents, time of the yeat etc. but assuming we play 19 La Liga games and 4-5 CL games at Camp Nou every season that's a loss of around 9m for every game played without fans. We've played a total of 6 home games (5 in La Liga + return leg vs Napoli) behind the closed doors and games against AM, Bilbao and Espanyol are usually amongst the most visited games every season. Just my assumption but I think it's pretty safe to say Barca have lost around 40-50m of planned revenues here as well.
Now when it comes to UEFA money Barca got 117m (the most from all participating teams) in 2018/19 mainly due to the "historic coefficient". IIRC the club always calculate qualifying to the semi-finals of the CL when setting up their budget for following season and with prize money this would be around 60m. Out of that money according to my math the club received 37m before June 30th. (15,25m for qualifying to the CL, 12,6m for results in group stage and 9,5m for qualifying to the last 16 round). What we've missed out is 10m for qualifying to the quarter-final (again the club eventually got that money but it shouldn't be accounted to last season/fiscal year) and 12m for not qualifying to the semi-final which they've planned to do.
It's hard to say how much money exactly we've lost from UEFA TV distribution but we've played at least 3 games less than expected before June (return leg vs Napoli and two matches vs Bayern) so again could easily be around 15m.
Commercial revenues - most important sponsorship deals (like Nike and Rakuten) are on longer term contracts so the club probably already received that money before corona crisis. But I think they've also lost some (probably tens of) millions with other smaller sponsors because they couldn't "show their names" in games on Camp Nou or be otherwise linked to the club during a corona crisis.
So it's not so far fetched to expect the club's revenues will be around that 850m mark I've mentioned above. Or lower, but I don't expect them to drop below 800m tbh.
Now how much a net loss will be it depends on the expenditures which were expected to be 1B with sporting salaries (without depreciation) representing half of that. There were reports of the club saving around 16m every month during the crisis so in 3 months (April-June) this is about 50m savings. IIRC from reports from previous years the club also accounts around 15-20m for players/coaching staff's bonuses for winning La Liga and/or domestic double (I think the later but not sure) every season. Which obivously didn't happen so more money saved (thanks Setien I guess
). Hopefully they've also reduced management costs but I think in best case scenario total expenditures will be around 930-950m so a net loss will be somewhere around 100-150m.