What are the major KPI to evaluate the success of the launch of a new product?

Ofcourse the relevant KPIs should be defined based on the industry, market, product and consumer.
In my opinion the KPIs related to the evaluation of the Consumer Behavior are the most important.
At that initial stage of launching a new product we should not be worried about revenue or profit, we shoould however be worried about Repeat Purchase Rate, Shelf Response, Consumer Perception, Price Resoponse, Brand/Messsage Recall, Product Concept Evaluation and many more.

Based on new product launch, there are multiple indicator to review it performance and few of them are;

1-      Target Vs. Achievement ( for e.g., if monthly financial target was50,000 per month then at the end of the month what was the achieved value.

2-      Target Unit Sold ( Initially based on the market or area what was the unit et per territory.)

3-      Apart from quantitative targets, # of Activities planned for the product promotion or penetration. (To enhance brand image and its prescription or value, what are the activities planned for KOLs)

4-      If a product has been launched few months or quarter back then to enhance the market share. Like moving from current share(20%) to30%.

5-      Allocation & utilization of budget for each product os SKUs.

6-      Return on Investment (ROIs) this is one of the core KPI for any brand or product where over impact has been monitored against the value and expense. This required an in-depth availability of data or analytic and this should be present by brand manager or business manager.

These are the some of the core KPIs for review of the performance any brand and next step to be plan on the basis of the performance.

financial resources Human resources natural resources needed time

time to market and market share evolution

Depends on the strategy you're using.
One of the most important things is to keep seeling an article for as long as possible, as long as the selling is profitable, so one should begin by analysing not only the cost of making but much more importan the cost of distribution.
This last KPI is perhaps the one that will on the long term determine the launch and selling of the new produtc.
So in my opinion the KPI of the supply chain and logistics are the most important!