Russia is consistently losing 20 to 25 artillery guns a day, you would think that would create not only logistical problems with having to bring up new equipment to replace what's been lost but gaps in the line where there is no artillery to cover areas where Ukraine is attacking.
Russia has loads of artillery and that'll be everything from large SPG's to the smaller towed stuff, logistically it's probably not that much of a massive job across the front and given the way artillery is meant to be placed you'd problably need to lose a lot more than 20-25 across several hundreds of miles of front for there to be a noticeable gap.
Remember these guns can fire 20-50 miles with ease and are often in groups of 5+, with additional groups within a few miles which means that you could lose an entire group and still have most of the area covered due to the overlapping fields of fire from other groups, and most of the time it's likely to be one or two guns in a position that are taken out at any one time (at least if they're set up properly in regards to placement and spacing*) unless you hit the area they are in very heavily.
To create a meaningful gap in the artillery you need to basically destroy or disable a number of guns from neighbouring positions in the same area at about the same time (so all those losses would need to be in the same area), otherwise you generally reduce the range and density but not really a gap.
Even if you don't destroy the guns, you can suppress them by firing at them, or by killing/wounding the troops servicing them which won't necessarily destroy the guns but will make them combat ineffective (there is a reason armoured SPG's that can operate and even resupply without exposing troops are an increasingly big thing for modern armies**).
The bigger problem with losing that number of guns a day is that they'll likely be losing a lot more of the trained men and thus team cohesion, so you might still be able to keep the number of guns up but the ability of them to fire quickly, accurately and as a group is lost resulting in slower rates of fire, more misses, and more chance of dangerous mistakes (ranging from small but debilitating injuries as fingers/hands get caught in mechanisms, to potential for explosions).
*You are meant to space them so that a single hit shouldn't take out more than one, preferably so that even if the "ready" ammo by a gun goes up it shouldn't take out additional guns (and ideally I believe with at least earthen barriers to give a little protection to the sides).
**IIRC South Korea make a very popular system that basically has a good rate of fire, good protection and can be entirely reloaded without the soldiers ever stepping outside of it's armoured hull.
