There is no hard limit.
Steem currently has an inflation of about 8% which decreases to 0.95% in the coming years.
Inflation narrows 0.01% every 250k blocks, since HF16. At block 7,000,000, there was a 9.5% instantaneous inflation rate, decreasing to 0.95% at this rate of 0.01% every 250k blocks. This narrowing will take approximately 20.5 years and will complete on block 220,750,000.
Source: https://developers.steem.io/tutorials-recipes/understanding-configuration-values
How does this inflation helps when is there an unlimited amount of supply.. one day will come when there will be no buyer left.. what happens then?