Does growing DPU means growing revenue for a business or indicating a strong business growth?

Not necessarily. Take a look at Starhub case study. Few years back, the company is already not doing well. However they still try to remain unrealistic dividends. Eventually, the stock price went down due to the unstable financial.

The most important aspect of the company is it's fundamentals, their management and also cash flow. Cash flow is important in times like this. (Take a look at SIA for another example)