BRS AMS for example is about 300k pax per year, based on the KLM schedule that says that EZY has about 65 percent of the market! Good for Amsterdam, bad for KLM.
In summer KLM has 4 rotations per day (2 on the F 70 and 2 on the E 190) except Saturday that sees 3 daily rotations (usually 2 x E 190 and 1 x F 70) which gives a weekly total of 4880 seats. easyJet has 10 rotations per week (daily except Sun, Mon and Fri which are double daily with the usual breakdown of aircraft being 7 x A 319 and 3 x A 320) which gives a weekly total of 3264 seats. This means that KLM has just under 60% of the available seats.
The latest CAA available stats are for June which show that 28,220 used the BRS-AMS route split between the 34,752 seats of both airlines meaning that just over 81% of seats were occupied.
If all easyJet flights were 100% full (highly unlikely) KLM would still have carried a few hundred more passengers than easyJet with a load factor around 68-69%.
The likelihood is that easyJet was nearer 90% load factor which would put KLM in the mid 70s%, with the latter carrying about 3,000 more passengers in the month than easyJet.
It's true that for the five winter months KLM drops to 3 x daily whilst easyJet maintains its summer schedule which puts the available seats in winter near parity and easyJet's probable higher load factor might give them an edge in terms of the number of passengers carried, but I can't see how easyJet can have anywhere near 65% of the market, even in winter.