Ivan, when you state "French offensive" I'm assuming you are speaking of the Saar Offensive. Simply put, On 7 September Eleven French divisions advanced along a 32 km line near Saarbrücken against weak German opposition. The French army had advanced to a depth of eight kilometers and captured about 20 villages evacuated by the German army, without any resistance. However, the half-hearted offensive was halted after France seized the Warndt Forest, three square miles of heavily-mined German territory.
As to your second question In fact, the allied forces were, on paper, far superior to their German opponents There were 117 French divisions in total, of which 104 divisions (including 11 in reserve) were for the defense of the north. The British Army contributed only 13 divisions, three of which had not been organized when the campaign began. Some 22 Belgian and 10 Dutch divisions were also a part of the Allied order of battle. British artillery strength amounted to 1,280 guns. Belgium fielded 1,338 and the Dutch, 656. France had 10,700 pieces. This made a total of around 14,000 artillery pieces. Although the Dutch, British and Belgians had barely any amour, the French had a powerful force of 3,254 tanks.
The French Army was of mixed quality. It had in its order of battle some formidable units, particularly the light and heavy armored divisions (DCR and DLM), and several professional infantry divisions. However, a lot of divisions were composed of reserve soldiers, above 30 years old, and were ill-equipped. A serious qualitative deficiency was a lack of anti-air artillery, mobile anti-tank artillery and radio communication systems. This was despite the efforts of Gamelin to produce mobile artillery units. French anti-tank guns were better than their German counter-parts, being able to destroy any German tank, including the Panzer IV, but some units, particularly in the Sedan area where the main German amour attack took place, were ill-equipped and composed of reserve soldiers. The French had the most powerful tanks in the world in 1940, with the Somua S35 Cavalry tank and the Renault B1bis Heavy tank, both being able to destroy all German tanks with their 47mm gun, and also being able to resist shots from German tanks and AT guns thanks to their thicker amour. Unfortunately, the French armored divisions did not have air support as the Germans did, and many French tanks were destroyed by German Stukas, or, even worse, ran out of fuel during combat. Unfortunately for the French, in 1940, French military theoreticians still considered tanks as infantry support.
In operational terms, the French did not seem to give much thought to armored units as offensive weapons. Although some people, such as Colonel de Gaulle, tried to convince French High Command, during the 1930s, of the necessity to form amour divisions supported by aviation and infantry, military conservatism prevented these "new ideas" from emerging. French High Command was still obsessed with holding the front like in 1914-1918. The state of training was also unbalanced, with the majority of personnel trained only to man static fortifications. Little training for mobile actions was carried out between September 1939 and May 1940.
Germany had mobilized 4,200,000 men for the Army, 1,000,000 for the Luftwaffe, 180,000 for the Kriegsmarine, and 100,000 of the Waffen-SS. When consideration is made for those in Poland, Denmark and Norway, the Army had 3,000,000 men available for the offensive on 10 May 1940. These manpower reserves were formed into 157 divisions. Of these, 135 were earmarked for the offensive, including 42 reserve divisions. Thus just 93 divisions began the offensive.
The German forces in the West in May and June deployed some 2,439 tanks and 7,378 artillery guns, including materiel reserves committed. In 1939–40, 45% of the army was 40-years-old, and 50% of all the soldiers had just a few weeks training. The German Army, contrary to what the blitzkrieg legend suggests, was not fully motorized. Just 10% of the Army was motorized in 1940 and could muster only 120,000 vehicles compared to the 300,000 of the French Army. The British also had an "enviable" contingent of motorized forces. Most of the German logistical tail consisted of horse-drawn vehicles.
Only 50% of the German divisions available in 1940 were combat ready, often being more poorly equipped than their equivalents in the British and French Armies, or even as well as the German Army of 1914. In the spring of 1940, the German army was semi-modern. A small number of the best equipped and "elite divisions were offset by many second and third rate divisions".
So could this German Army continue after being mauled in Poland into the face of fresh Allied divisions? Highly unlikely