April 14 (Reuters) - Canada’s main stock index gained on Wednesday as investors expect fiscal stimulus measures that will be announced next week to be huge, while a jump in oil prices supported the commodity-heavy index. * At 9:30 a.m. ET (13:30 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was up 59.9 points, or 0.31%, at 19,263.6. (Reporting by Shashank Nayar in Bengaluru; Editing by Shinjini Ganguli)