CANADA'S visiting head of state raised the subject of the territory's future in meetings with Chinese President Jiang Zemin and the Hong Kong and Macau Affairs Office head Lu Ping, but received little assurance. Governor-General Ramon Hnatyshyn, who is the Queen's representative and official head of state in Canada, met Mr Jiang and Mr Lu during a trip to Beijing last week and arrived in Hong Kong on Friday, when he met Governor Chris Patten. He told Mr Jiang that Canada had a stake in Hong Kong's future because of the large number of Hong Kong Chinese who had become Canadian citizens and because of Canadian investment in the territory. Mr Hnatyshyn stressed to Mr Jiang and Mr Lu that the 1984 Joint Declaration should be abided by and said Canada wanted stability, prosperity and autonomy for Hong Kong after 1997. But the Chinese response was non-committal. ''Mr Lu listened carefully, acknowledged that there were challenges, but his remarks were that he wanted the transition to go smoothly,'' one Canadian official said. Mr Jiang's response was not revealed.