José Manuel Amat, a pioneer and a firm believer in, and promoter of, the tourism potential of the Dominican Republic, died last week of cancer in Madrid, much before his time. Mr. Amat was the man behind the building up of the Occidental Hotels chain in the country. A man of vision, since the time the Spanish chain took over the management of the Hotel Embajador in 1983, he sought to continue adding hotels up to the company’s portfolio, presently numbering 11 hotels, with a total of 56 throughout the world. In 1992 he won the most important Spanish travel industry award, the “Premio Anual de Turismo,” as a recognition of his 35 years in the industry.