144,000 cats die each day in the world. 14,600 die a day in the USA and 1,800 die a day in the UK. These are my estimates based on average lifespans. They are for domestic cats (not including feral and stray cats) for the USA and UK and for the world the figure is for both feral and domestic. Wild cat deaths would not make a significant difference to these figures as the proportion of wildcats to domestic cats is small.
These figures have not taken into account the approximate 1 million domestic cats (i.e. not feral) cats that are deliberately killed each year at shelters nor the cats shot and abused. Factor that in and the figures will be higher by a considerable percentage.
The calculation is based on this model: If there were 15 cats in the world and all fifteen where born on separate years and all the cats had a lifespan on 15 years, one cat would die per year which is one-fifteenth (6.67%) of the total. So 6.67% of all cats die per year. If you find fault in that please tell me in a comment and I will correct the maths.
The figures are set out in the spreadsheet below:
The figures above are for natural deaths with an average age of 15 years. If we recalculate for feral cats at an average life span of say 4 years we get these figures: 54,000 feral cats per day die in the USA, 6,800 die a day in the UK and 205,000 die a day in the world.