According to a study by Nobel Prize winning economists over 10 years ago, more money can in fact lead to more happiness, and that feeling plateaus around $75,000 a year. According to them, having less money than that increased sadness, but having more money didn't help feel happy. However, a new study has gone the other way completely. 

The new study, titled Experienced well-being rises with income, even above $75,000 per year, says that happiness increases beyond that amount as well.

There was no evidence of an income threshold at which experienced and evaluative well-being diverged, suggesting that higher incomes are associated with both feeling better day-to-day and being more satisfied with life overall.
Source: Money Control

The study is based on 1,725,994 samples conducted on 33,391 employed people in the US. It detailed 'experienced well-being', which is a measure of happiness taken in the moment 

The study was conducted by Matt Killingsworth, a senior fellow at Wharton School for Business at the University of Pennsylvania. It also utilised evaluative well-being, which is an overall evaluation of a person’s life divorced from a particular moment.

We’re finding similar patterns for evaluative well-being and similar patterns in a variety of other ways in the data. Findings show that happiness doesn’t plateau at the $75,000 mark.
Source: Economic Times

Despite all this however, one thing Matt found consistently true across all his subjects was that anyone who equated money with personal success was extremely unhappy,