A few points to take away from that, firstly should be obvious in as much as by concentrating such a large amount of their army in one area is allow Ukraine to counter attack elsewhere. Secondly we know that Russia has had to conscript men of fighting age in the DPR and LPR and press them into the front lines (often with no body armour or sometimes with bygone weapons) so whilst Ukraine is outnumbered the overall quality of units doing the fighting is mixed at best (some estimates have put the potential numbers of DPR and LPR conscripts at around d 20k to 30k). Lastly Ukraine is still mobilising it's army, at this point there using more and more 2nd file troops/reservists/national guard to plug gaps and in the background they are trying to raise some 700k to a 1m new troops but to train and arm that many men will take many, many months. Ultimately the plan is to try and fight Russian to a standstill and when Ukraine has the weapons it's asked for and the forces sufficiently trained it will go on a general offensive to drive Russia out.
As it stands although Russia is having some success it's a massive price in terms of manpower and equipment, without a general mobilsation it's questionable how much further they can go. There biggest trump card is their artillery, their effective with it and they have a lot of it, I'm not sure Ukraine even with NATO help will every be able to outgun Russia but from the recent videos on Twitter and Reddit etc it looks like Ukraine is trying to target the ammounition dumps and command posts which at the moment are within range of the new MLRS's systems they've been given. The only certainty is a lot more people will die before this war is over.