From: Hobart, Tasmania, Australia
Stalin, and the Russians in general, lied through their back teeth about almost everything to the Western Allies. They were outrageously paranoid and always tried to skew circumstances so as to complain about their share of the war effort.
In prisoners alone, they lost approximately 3 million soldiers from June 22 1941 to the end of the year. Losses were so heavy that by the Autumn of 1941 new recruits to the Red Army were often given barely any (or no) training at all before being thrown into combat. An offer to provide troops for a second front in 1941 was almost certainly one of Stalin's ruses. There may have been something to it if it occurred very early on (before the horrific losses) but even then, the logistical problems of transporting the tens of thousands of troops to Britain would have been enormous. Would the British have to arm them? They had their hands full producing enough weapons for their own army. If not, all their equipment would need transporting too. Much better to just use them on the Eastern Front. In short, bollocks.
People often talk blithely about unlimited Russian manpower but the facts are otherwise. Apart from the hideous losses in 1941, Stalin insisted on continuing the winter counter-offensive for too long in early 1942 and then the Red Army launched their disastrous and costly Kharkov attack in May 1942, leaving it very short of men for some time. Although the Russians recovered to go over to the general offensive in November 1942 and win great victories in 1943 and 1944 their relatively unsophisticated tactics and general profligacy with regard to casualties meant that by mid 1944 they were running out of men. Although many freed Soviet POWs and forced labourers were sent to the GULAG, most were actually quickly pressed into military service, such was the desperate need to flesh out Red Army formations.