Once upon a time air forces commonly had more aircraft than pilots. A first-line fighter of World War II cost about $50,000. Today’s top-of-the line fighters cost much more. After allowing for inflation on a generous scale, there is still probably a 15 times increase. So today there are more pilots than aircraft. Each aircraft lost for combat or combat related reasons, even if the pilot is lost or badly hurt, which, is not always the case, means another one or two pilots without an aircraft.
New aircraft are very difficult to come by because manufacturers produce only on firm order, and take two years or more for delivery.
The only way to get fast replacements is from friendly nations.
The PAF has much smaller pool of fighter pilots, being a much smaller air force. This may not matter in a short war. In a long war, however, one lives off the fat till new pilots are trained, and as India has ample fat, the advantage is theirs. Admittedly the replacement pilots may not be as good as the first-line ones. But as the best ones disappear, or survive to get better, the not-so-good pilots become adequate in comparison to the enemy, who is also losing his good pilots.